{"id":"CVE-2026-35186","aliases":["DEBIAN-CVE-2026-35186","EUVD-2026-21037","GHSA-f984-pcp8-v2p7","JLSEC-2026-1363","RUSTSEC-2026-0094","SUSE-SU-2026:21789-1","UBUNTU-CVE-2026-35186","openSUSE-SU-2026:10715-1","openSUSE-SU-2026:20749-1"],"status":"published","title":"Wasmtime has an improperly masked return value from `table.grow` with Winch compiler backend","description":"Wasmtime is a runtime for WebAssembly. From 25.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime's Winch compiler backend contains a bug where translating the table.grow operator causes the result to be incorrectly typed. For 32-bit tables this means that the result of the operator, internally in Winch, is tagged as a 64-bit value instead of a 32-bit value. This invalid internal representation of Winch's compiler state compounds into further issues depending on how the value is consumed. The primary consequence of this bug is that bytes in the host's address space can be stored/read from. This is only applicable to the 16 bytes before linear memory, however, as the only significant return value of table.grow that can be misinterpreted is -1. The bytes before linear memory are, by default, unmapped memory. Wasmtime will detect this fault and abort the process, however, because wasm should not be able to access these bytes. Overall this this bug in Winch represents a DoS vector by crashing the host process, a correctness issue within Winch, and a possible leak of up to 16-bytes before linear memory. Wasmtime's default compiler is Cranelift, not Winch, and Wasmtime's default settings are to place guard pages before linear memory. This means that Wasmtime's default configuration is not affected by this issue, and when explicitly choosing Winch Wasmtime's otherwise default configuration leads to a DoS. Disabling guard pages before linear memory is required to possibly leak up to 16-bytes of host data. This vulnerability is fixed in 36.0.7, 42.0.2, and 43.0.1.","severity":{"version":"4.0","score":6.1,"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00222,"percentile":0.12868,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-789"],"published":"2026-04-09T12:00:00Z","modified":"2026-10-28T02:30:27Z","fixes":[{"ecosystem":"crates.io","package":"wasmtime","fixed_in":["36.0.7","42.0.2","43.0.1"],"sources":["ghsa","osv"]},{"ecosystem":"Debian:14","package":"rust-wasmtime","fixed_in":["36.0.7+dfsg-1"],"sources":["osv"]},{"ecosystem":"Julia","package":"Wasmtime_jll","fixed_in":["45.0.1+0"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"crates.io","package":"wasmtime","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"25.0.0"},{"fixed":"36.0.7"}]}]},{"source":"ghsa","ecosystem":"crates.io","package":"wasmtime","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"37.0.0"},{"fixed":"42.0.2"}]}]},{"source":"ghsa","ecosystem":"crates.io","package":"wasmtime","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"43.0.0"},{"last_affected":"43.0.0"},{"fixed":"43.0.1"}]}],"versions":["43.0.0"]},{"source":"osv","ecosystem":"Debian:13","package":"rust-wasmtime","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["26.0.1+dfsg-10","26.0.1+dfsg-3","26.0.1+dfsg-4","26.0.1+dfsg-5","26.0.1+dfsg-6","26.0.1+dfsg-7","26.0.1+dfsg-8","26.0.1+dfsg-9","27.0.0+dfsg-2","27.0.0+dfsg-3","27.0.0+dfsg-4","28.0.1+dfsg-1","28.0.1+dfsg-2","28.0.1+dfsg-3","29.0.1+dfsg-1","29.0.1+dfsg-2","29.0.1+dfsg-3","29.0.1+dfsg-4","29.0.1+dfsg-5","29.0.1+dfsg-6","29.0.1+dfsg-7","29.0.1+dfsg-8","36.0.11+dfsg-1","36.0.12+dfsg-1","36.0.12+dfsg-2","36.0.12+dfsg-3","36.0.13+dfsg-1","36.0.5+dfsg-1","36.0.5+dfsg-2","36.0.5+dfsg-3","36.0.5+dfsg-4","36.0.5+dfsg-5","36.0.6+dfsg-1","36.0.6+dfsg-2","36.0.6+dfsg-3","36.0.6+dfsg-4","36.0.6+dfsg-5","36.0.6+dfsg-6","36.0.6+dfsg-7","36.0.7+dfsg-1","36.0.8+dfsg-1","36.0.9+dfsg-1","36.0.9+dfsg-2"]},{"source":"osv","ecosystem":"Debian:14","package":"rust-wasmtime","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"36.0.7+dfsg-1"}]}],"versions":["26.0.1+dfsg-10","26.0.1+dfsg-3","26.0.1+dfsg-4","26.0.1+dfsg-5","26.0.1+dfsg-6","26.0.1+dfsg-7","26.0.1+dfsg-8","26.0.1+dfsg-9","27.0.0+dfsg-2","27.0.0+dfsg-3","27.0.0+dfsg-4","28.0.1+dfsg-1","28.0.1+dfsg-2","28.0.1+dfsg-3","29.0.1+dfsg-1","29.0.1+dfsg-2","29.0.1+dfsg-3","29.0.1+dfsg-4","29.0.1+dfsg-5","29.0.1+dfsg-6","29.0.1+dfsg-7","29.0.1+dfsg-8","36.0.5+dfsg-1","36.0.5+dfsg-2","36.0.5+dfsg-3","36.0.5+dfsg-4","36.0.5+dfsg-5","36.0.6+dfsg-1","36.0.6+dfsg-2","36.0.6+dfsg-3","36.0.6+dfsg-4","36.0.6+dfsg-5","36.0.6+dfsg-6","36.0.6+dfsg-7"]},{"source":"osv","ecosystem":"crates.io","package":"wasmtime","ranges":[{"type":"SEMVER","events":[{"introduced":"25.0.0"},{"fixed":"36.0.7"}]}]},{"source":"osv","ecosystem":"crates.io","package":"wasmtime","ranges":[{"type":"SEMVER","events":[{"introduced":"37.0.0"},{"fixed":"42.0.2"}]}]},{"source":"osv","ecosystem":"crates.io","package":"wasmtime","ranges":[{"type":"SEMVER","events":[{"introduced":"43.0.0"},{"fixed":"43.0.1"}]}],"versions":["43.0.0"]},{"source":"osv","ecosystem":"Julia","package":"Wasmtime_jll","ranges":[{"type":"SEMVER","events":[{"introduced":"39.0.0+0"},{"fixed":"45.0.1+0"}]}]},{"source":"osv","ecosystem":"crates.io","package":"wasmtime","ranges":[{"type":"SEMVER","events":[{"introduced":"0.0.0-0"},{"fixed":"36.0.7"},{"introduced":"37.0.0"},{"fixed":"42.0.2"},{"introduced":"43.0.0"},{"fixed":"43.0.1"}]}]},{"source":"osv","ecosystem":"Ubuntu:24.04:LTS","package":"rust-wasmtime","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["10.0.1+dfsg-7","15.0.1+dfsg-4","16.0.0+dfsg-2","16.0.0+dfsg-3"]},{"source":"osv","ecosystem":"Ubuntu:25.10","package":"rust-wasmtime","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["26.0.1+dfsg-3"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"rust-wasmtime","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["36.0.5+dfsg-1","36.0.13+dfsg-1"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"rust-wasmtime","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["26.0.1+dfsg-3","26.0.1+dfsg-4","28.0.1+dfsg-3","29.0.1+dfsg-5","36.0.5+dfsg-1"]},{"source":"osv","ecosystem":"openSUSE:Tumbleweed","package":"tree-sitter","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.26.8-2.1"}]}],"bundled":4}],"products":[{"vendor":"bytecodealliance","product":"wasmtime"}],"references":[{"url":"https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-f984-pcp8-v2p7","tags":["x_refsource_CONFIRM","Vendor Advisory","advisory","web","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-35186","tags":["advisory","web"]},{"url":"https://rustsec.org/advisories/RUSTSEC-2026-0094.html","tags":["web","advisory"]},{"url":"https://github.com/advisories/GHSA-f984-pcp8-v2p7","tags":["web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/35xxx/CVE-2026-35186.json","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-35186","tags":["advisory"]},{"url":"https://github.com/bytecodealliance/wasmtime","tags":["package"]},{"url":"https://crates.io/crates/wasmtime","tags":["package"]},{"url":"https://github.com/bytecodealliance/wasmtime/pull/13014","tags":["web"]},{"url":"https://www.suse.com/support/update/announcement/2026/suse-su-202621789-1/","tags":["advisory"]},{"url":"https://bugzilla.suse.com/1259205","tags":["report"]},{"url":"https://bugzilla.suse.com/1261839","tags":["report"]},{"url":"https://bugzilla.suse.com/1261871","tags":["report"]},{"url":"https://bugzilla.suse.com/1261894","tags":["report"]},{"url":"https://bugzilla.suse.com/1261954","tags":["report"]},{"url":"https://bugzilla.suse.com/1261963","tags":["report"]},{"url":"https://bugzilla.suse.com/1261968","tags":["report"]},{"url":"https://bugzilla.suse.com/1261974","tags":["report"]},{"url":"https://bugzilla.suse.com/1262007","tags":["report"]},{"url":"https://bugzilla.suse.com/1262032","tags":["report"]},{"url":"https://bugzilla.suse.com/1262036","tags":["report"]},{"url":"https://bugzilla.suse.com/1262040","tags":["report"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34941","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34942","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34943","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34944","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34945","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34946","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34987","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34988","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-35186","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-35195","tags":["web"]},{"url":"https://ubuntu.com/security/CVE-2026-35186","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-35186","tags":["report"]},{"url":"","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-35186","title":"Wasmtime has an improperly masked return value from `table.grow` with Winch compiler backend","description":"Wasmtime is a runtime for WebAssembly. From 25.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime's Winch compiler backend contains a bug where translating the table.grow operator causes the result to be incorrectly typed. For 32-bit tables this means that the result of the operator, internally in Winch, is tagged as a 64-bit value instead of a 32-bit value. This invalid internal representation of Winch's compiler state compounds into further issues depending on how the value is consumed. The primary consequence of this bug is that bytes in the host's address space can be stored/read from. This is only applicable to the 16 bytes before linear memory, however, as the only significant return value of table.grow that can be misinterpreted is -1. The bytes before linear memory are, by default, unmapped memory. Wasmtime will detect this fault and abort the process, however, because wasm should not be able to access these bytes. Overall this this bug in Winch represents a DoS vector by crashing the host process, a correctness issue within Winch, and a possible leak of up to 16-bytes before linear memory. Wasmtime's default compiler is Cranelift, not Winch, and Wasmtime's default settings are to place guard pages before linear memory. This means that Wasmtime's default configuration is not affected by this issue, and when explicitly choosing Winch Wasmtime's otherwise default configuration leads to a DoS. Disabling guard pages before linear memory is required to possibly leak up to 16-bytes of host data. This vulnerability is fixed in 36.0.7, 42.0.2, and 43.0.1.","status":"published","published":"2026-04-09T18:54:48.76Z","modified":"2026-04-13T20:18:21.954Z","cvss":[{"version":"4.0","score":6.1,"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N","level":"medium","assessor":"cna"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"adp"}],"cwes":["CWE-789"],"updated_at":"2026-11-02T14:20:05.15083Z"}],"euvd":[{"id":"EUVD-2026-21037","description":"Wasmtime is a runtime for WebAssembly. From 25.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime's Winch compiler backend contains a bug where translating the table.grow operator causes the result to be incorrectly typed. For 32-bit tables this means that the result of the operator, internally in Winch, is tagged as a 64-bit value instead of a 32-bit value. This invalid internal representation of Winch's compiler state compounds into further issues depending on how the value is consumed. The primary consequence of this bug is that bytes in the host's address space can be stored/read from. This is only applicable to the 16 bytes before linear memory, however, as the only significant return value of table.grow that can be misinterpreted is -1. The bytes before linear memory are, by default, unmapped memory. Wasmtime will detect this fault and abort the process, however, because wasm should not be able to access these bytes. Overall this this bug in Winch represents a DoS vector by crashing the host process, a correctness issue within Winch, and a possible leak of up to 16-bytes before linear memory. Wasmtime's default compiler is Cranelift, not Winch, and Wasmtime's default settings are to place guard pages before linear memory. This means that Wasmtime's default configuration is not affected by this issue, and when explicitly choosing Winch Wasmtime's otherwise default configuration leads to a DoS. Disabling guard pages before linear memory is required to possibly leak up to 16-bytes of host data. This vulnerability is fixed in 36.0.7, 42.0.2, and 43.0.1.","status":"published","published":"2026-04-09T18:54:48Z","modified":"2026-04-13T20:18:21Z","cvss":[{"version":"4.0","score":6.1,"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N","level":"medium"}],"updated_at":"2026-11-02T19:24:27.052992Z"}],"ghsa":[{"id":"GHSA-f984-pcp8-v2p7","title":"Wasmtime has improperly masked return value from `table.grow` with Winch compiler backend","description":"### Impact\n\nWasmtime's Winch compiler backend contains a bug where translating the `table.grow` operator causes the result to be incorrectly typed. For 32-bit tables this means that the result of the operator, internally in Winch, is tagged as a 64-bit value instead of a 32-bit value. This invalid internal representation of Winch's compiler state compounds into further issues depending on how the value is consumed.\n\nOne example can be seen when the result of `table.grow` is used as the address of a load operation. The load operation is tricked into thinking the address is a 64-bit value, not a 32-bit value, which means that the final address to load from is calculated incorrectly. This can lead to a situation where the bytes before the start of linear memory can be loaded/stored to.\n\nThe primary consequence of this bug is that bytes in the host's address space can be stored/read from. This is only applicable to the 16 bytes before linear memory, however, as the only significant return value of `table.grow` that can be misinterpreted is -1. The bytes before linear memory are, by default, unmapped memory. Wasmtime will detect this fault and abort the process, however, because wasm should not be able to access these bytes.\n\nOverall this this bug in Winch represents a DoS vector by crashing the host process, a correctness issue within Winch, and a possible leak of up to 16-bytes before linear memory. Wasmtime's default compiler is Cranelift, not Winch, and Wasmtime's default settings are to place guard pages before linear memory. This means that Wasmtime's default configuration is not affected by this issue, and when explicitly choosing Winch Wasmtime's otherwise default configuration leads to a DoS. Disabling guard pages before linear memory is required to possibly leak up to 16-bytes of host data.\n\n### Patches\n\nWasmtime 43.0.1, 42.0.2, and 36.0.7 have been released with fixes for this issue.\n\n### Workaround\n\nThere are no workarounds within the Winch compiler backend while using the affected versions. Users of Wasmtime are encouraged either to upgrade to patched versions or, if that is not possible, use the Cranelift compiler backend.","status":"published","published":"2026-04-10T15:32:49Z","modified":"2026-04-10T15:32:54Z","cvss":[{"version":"4.0","score":6.1,"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N","level":"medium"}],"cwes":["CWE-789"],"updated_at":"2026-11-02T14:39:52.102227Z"}],"nvd":[{"id":"CVE-2026-35186","description":"Wasmtime is a runtime for WebAssembly. From 25.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime's Winch compiler backend contains a bug where translating the table.grow operator causes the result to be incorrectly typed. For 32-bit tables this means that the result of the operator, internally in Winch, is tagged as a 64-bit value instead of a 32-bit value. This invalid internal representation of Winch's compiler state compounds into further issues depending on how the value is consumed. The primary consequence of this bug is that bytes in the host's address space can be stored/read from. This is only applicable to the 16 bytes before linear memory, however, as the only significant return value of table.grow that can be misinterpreted is -1. The bytes before linear memory are, by default, unmapped memory. Wasmtime will detect this fault and abort the process, however, because wasm should not be able to access these bytes. Overall this this bug in Winch represents a DoS vector by crashing the host process, a correctness issue within Winch, and a possible leak of up to 16-bytes before linear memory. Wasmtime's default compiler is Cranelift, not Winch, and Wasmtime's default settings are to place guard pages before linear memory. This means that Wasmtime's default configuration is not affected by this issue, and when explicitly choosing Winch Wasmtime's otherwise default configuration leads to a DoS. Disabling guard pages before linear memory is required to possibly leak up to 16-bytes of host data. This vulnerability is fixed in 36.0.7, 42.0.2, and 43.0.1.","status":"published","published":"2026-04-09T19:16:25.343Z","modified":"2026-10-26T22:10:00.163Z","cvss":[{"version":"4.0","score":6.1,"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"medium","assessor":"secondary"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"secondary"}],"cwes":["CWE-789"],"updated_at":"2026-11-02T14:12:13.902911Z"}],"osv":[{"id":"CVE-2026-35186","title":"Wasmtime has an improperly masked return value from `table.grow` with Winch compiler backend","description":"Wasmtime is a runtime for WebAssembly. From 25.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime's Winch compiler backend contains a bug where translating the table.grow operator causes the result to be incorrectly typed. For 32-bit tables this means that the result of the operator, internally in Winch, is tagged as a 64-bit value instead of a 32-bit value. This invalid internal representation of Winch's compiler state compounds into further issues depending on how the value is consumed. The primary consequence of this bug is that bytes in the host's address space can be stored/read from. This is only applicable to the 16 bytes before linear memory, however, as the only significant return value of table.grow that can be misinterpreted is -1. The bytes before linear memory are, by default, unmapped memory. Wasmtime will detect this fault and abort the process, however, because wasm should not be able to access these bytes. Overall this this bug in Winch represents a DoS vector by crashing the host process, a correctness issue within Winch, and a possible leak of up to 16-bytes before linear memory. Wasmtime's default compiler is Cranelift, not Winch, and Wasmtime's default settings are to place guard pages before linear memory. This means that Wasmtime's default configuration is not affected by this issue, and when explicitly choosing Winch Wasmtime's otherwise default configuration leads to a DoS. Disabling guard pages before linear memory is required to possibly leak up to 16-bytes of host data. This vulnerability is fixed in 36.0.7, 42.0.2, and 43.0.1.","status":"published","published":"2026-04-09T18:54:48.76Z","modified":"2026-10-28T02:30:27.734363563Z","cvss":[{"version":"4.0","score":6.1,"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N","level":"medium"}],"cwes":["CWE-789"],"updated_at":"2026-11-02T15:45:02.673625Z"},{"id":"DEBIAN-CVE-2026-35186","description":"Wasmtime is a runtime for WebAssembly. From 25.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime's Winch compiler backend contains a bug where translating the table.grow operator causes the result to be incorrectly typed. For 32-bit tables this means that the result of the operator, internally in Winch, is tagged as a 64-bit value instead of a 32-bit value. This invalid internal representation of Winch's compiler state compounds into further issues depending on how the value is consumed. The primary consequence of this bug is that bytes in the host's address space can be stored/read from. This is only applicable to the 16 bytes before linear memory, however, as the only significant return value of table.grow that can be misinterpreted is -1. The bytes before linear memory are, by default, unmapped memory. Wasmtime will detect this fault and abort the process, however, because wasm should not be able to access these bytes. Overall this this bug in Winch represents a DoS vector by crashing the host process, a correctness issue within Winch, and a possible leak of up to 16-bytes before linear memory. Wasmtime's default compiler is Cranelift, not Winch, and Wasmtime's default settings are to place guard pages before linear memory. This means that Wasmtime's default configuration is not affected by this issue, and when explicitly choosing Winch Wasmtime's otherwise default configuration leads to a DoS. Disabling guard pages before linear memory is required to possibly leak up to 16-bytes of host data. This vulnerability is fixed in 36.0.7, 42.0.2, and 43.0.1.","status":"published","published":"2026-04-09T19:16:25.343Z","modified":"2026-10-27T09:47:42.031995101Z","cvss":[{"version":"4.0","score":6.1,"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"medium"}],"updated_at":"2026-11-02T15:45:54.587575Z"},{"id":"GHSA-f984-pcp8-v2p7","title":"Wasmtime has improperly masked return value from `table.grow` with Winch compiler backend","description":"### Impact\n\nWasmtime's Winch compiler backend contains a bug where translating the `table.grow` operator causes the result to be incorrectly typed. For 32-bit tables this means that the result of the operator, internally in Winch, is tagged as a 64-bit value instead of a 32-bit value. This invalid internal representation of Winch's compiler state compounds into further issues depending on how the value is consumed.\n\nOne example can be seen when the result of `table.grow` is used as the address of a load operation. The load operation is tricked into thinking the address is a 64-bit value, not a 32-bit value, which means that the final address to load from is calculated incorrectly. This can lead to a situation where the bytes before the start of linear memory can be loaded/stored to.\n\nThe primary consequence of this bug is that bytes in the host's address space can be stored/read from. This is only applicable to the 16 bytes before linear memory, however, as the only significant return value of `table.grow` that can be misinterpreted is -1. The bytes before linear memory are, by default, unmapped memory. Wasmtime will detect this fault and abort the process, however, because wasm should not be able to access these bytes.\n\nOverall this this bug in Winch represents a DoS vector by crashing the host process, a correctness issue within Winch, and a possible leak of up to 16-bytes before linear memory. Wasmtime's default compiler is Cranelift, not Winch, and Wasmtime's default settings are to place guard pages before linear memory. This means that Wasmtime's default configuration is not affected by this issue, and when explicitly choosing Winch Wasmtime's otherwise default configuration leads to a DoS. Disabling guard pages before linear memory is required to possibly leak up to 16-bytes of host data.\n\n### Patches\n\nWasmtime 43.0.1, 42.0.2, and 36.0.7 have been released with fixes for this issue.\n\n### Workaround\n\nThere are no workarounds within the Winch compiler backend while using the affected versions. Users of Wasmtime are encouraged either to upgrade to patched versions or, if that is not possible, use the Cranelift compiler backend.","status":"published","published":"2026-04-10T15:32:49Z","modified":"2026-09-10T03:51:01.591759397Z","cvss":[{"version":"4.0","score":6.1,"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N","level":"medium"}],"cwes":["CWE-789"],"updated_at":"2026-11-02T15:46:46.006631Z"},{"id":"JLSEC-2026-1363","title":"Wasmtime has improperly masked return value from `table.grow` with Winch compiler backend","description":"### Impact\n\nWasmtime's Winch compiler backend contains a bug where translating the `table.grow` operator causes the result to be incorrectly typed. For 32-bit tables this means that the result of the operator, internally in Winch, is tagged as a 64-bit value instead of a 32-bit value. This invalid internal representation of Winch's compiler state compounds into further issues depending on how the value is consumed.\n\nOne example can be seen when the result of `table.grow` is used as the address of a load operation. The load operation is tricked into thinking the address is a 64-bit value, not a 32-bit value, which means that the final address to load from is calculated incorrectly. This can lead to a situation where the bytes before the start of linear memory can be loaded/stored to.\n\nThe primary consequence of this bug is that bytes in the host's address space can be stored/read from. This is only applicable to the 16 bytes before linear memory, however, as the only significant return value of `table.grow` that can be misinterpreted is -1. The bytes before linear memory are, by default, unmapped memory. Wasmtime will detect this fault and abort the process, however, because wasm should not be able to access these bytes.\n\nOverall this this bug in Winch represents a DoS vector by crashing the host process, a correctness issue within Winch, and a possible leak of up to 16-bytes before linear memory. Wasmtime's default compiler is Cranelift, not Winch, and Wasmtime's default settings are to place guard pages before linear memory. This means that Wasmtime's default configuration is not affected by this issue, and when explicitly choosing Winch Wasmtime's otherwise default configuration leads to a DoS. Disabling guard pages before linear memory is required to possibly leak up to 16-bytes of host data.\n\n### Patches\n\nWasmtime 43.0.1, 42.0.2, and 36.0.7 have been released with fixes for this issue.\n\n### Workaround\n\nThere are no workarounds within the Winch compiler backend while using the affected versions. Users of Wasmtime are encouraged either to upgrade to patched versions or, if that is not possible, use the Cranelift compiler backend.","status":"published","published":"2026-08-21T20:43:33.133Z","modified":"2026-08-21T21:14:20.068227329Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"},{"version":"4.0","score":6.1,"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"medium"}],"updated_at":"2026-11-02T15:47:18.159338Z"},{"id":"RUSTSEC-2026-0094","title":"Improperly masked return value from `table.grow` with Winch compiler backend","description":"This is an entry in the RustSec database for the Wasmtime security advisory\nlocated at\nhttps://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-f984-pcp8-v2p7\nFor more information see the GitHub-hosted security advisory.","status":"published","published":"2026-04-09T12:00:00Z","modified":"2026-10-12T18:00:08.331492925Z","cvss":[{"version":"4.0","score":6.1,"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N","level":"medium"}],"updated_at":"2026-11-02T15:53:40.430679Z"},{"id":"UBUNTU-CVE-2026-35186","description":"Wasmtime is a runtime for WebAssembly. From 25.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime's Winch compiler backend contains a bug where translating the table.grow operator causes the result to be incorrectly typed. For 32-bit tables this means that the result of the operator, internally in Winch, is tagged as a 64-bit value instead of a 32-bit value. This invalid internal representation of Winch's compiler state compounds into further issues depending on how the value is consumed. The primary consequence of this bug is that bytes in the host's address space can be stored/read from. This is only applicable to the 16 bytes before linear memory, however, as the only significant return value of table.grow that can be misinterpreted is -1. The bytes before linear memory are, by default, unmapped memory. Wasmtime will detect this fault and abort the process, however, because wasm should not be able to access these bytes. Overall this this bug in Winch represents a DoS vector by crashing the host process, a correctness issue within Winch, and a possible leak of up to 16-bytes before linear memory. Wasmtime's default compiler is Cranelift, not Winch, and Wasmtime's default settings are to place guard pages before linear memory. This means that Wasmtime's default configuration is not affected by this issue, and when explicitly choosing Winch Wasmtime's otherwise default configuration leads to a DoS. Disabling guard pages before linear memory is required to possibly leak up to 16-bytes of host data. This vulnerability is fixed in 36.0.7, 42.0.2, and 43.0.1.","status":"published","published":"2026-04-09T19:16:00Z","modified":"2026-10-17T13:00:02.202913045Z","cvss":[{"version":"4.0","score":6.1,"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N","level":"medium"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T16:56:16.686388Z"},{"id":"openSUSE-SU-2026:10715-1","title":"libtree-sitter0_26-0.26.8-2.1 on GA media","description":"These are all security issues fixed in the libtree-sitter0_26-0.26.8-2.1 package on the GA media of openSUSE Tumbleweed.","status":"published","published":"2026-05-06T00:00:00Z","modified":"2026-05-07T08:47:38.961758Z","updated_at":"2026-11-02T16:58:38.415593Z"},{"id":"openSUSE-SU-2026:20749-1","title":"Security update for tree-sitter","description":"This update for tree-sitter fixes the following issues\n\nSecurity issues:\n\n- CVE-2026-34941: wasmtime: crafted input string can lead to an out-of-bound read (bsc#1261871).\n- CVE-2026-34942: wasmtime: unaligned pointers can lead to a denial of service (bsc#1261894).\n- CVE-2026-34943: wasmtime: lifting `flags` component value can lead to a denial of service (bsc#1261954).\n- CVE-2026-34944: wasmtime: out-of-bounds read during WebAssembly compilation can lead to a denial of service\n  (bsc#1261963).\n- CVE-2026-34945: wasmtime: incorrectly translated table.size could lead to disclosing data (bsc#1262007).\n- CVE-2026-34946: wasmtime: denial of service due to WebAssembly compilation error (bsc#1261974).\n- CVE-2026-34987: wasmtime: winch compiler backend may allow a sandbox-escaping memory access (bsc#1262032).\n- CVE-2026-34988: wasmtime: pooling allocator instances can cause data leakage (bsc#1261968).\n- CVE-2026-35186: wasmtime: translating the table.grow operator can cause a masked return value (bsc#1262036).\n- CVE-2026-35195: wasmtime: transcoding strings can lead to an out of bound write or a crash (bsc#1262040).\n\nChanges for tree-sitter:\n\n- update to 0.26.8:\n\n * fix(generate): allow disabling qjs-rt feature from CLI by @WillLillis in\n #5448\n * fix(lib): document invariants that must be upheld for TSInputEdit by\n @WillLillis in #5452\n * fix(cli): correct typo in parse command's help text by @WillLillis in #5465\n * perf(cli): misc. improvements by @tree-sitter-ci-bot[bot] in #5476\n * Fix wasm loading of languages w/ multiple reserved word sets by\n @tree-sitter-ci-bot[bot] in #5477\n * generate: avoid panicking when a supertype only has hidden external token\n children by @tree-sitter-ci-bot[bot] in #5478\n","status":"published","published":"2026-05-14T08:07:53Z","modified":"2026-05-19T18:23:48.124613698Z","updated_at":"2026-11-02T16:58:41.463445Z"},{"id":"SUSE-SU-2026:21789-1","title":"Security update for tree-sitter","description":"This update for tree-sitter fixes the following issues\n\nSecurity issues:\n\n- CVE-2026-34941: wasmtime: crafted input string can lead to an out-of-bound read (bsc#1261871).\n- CVE-2026-34942: wasmtime: unaligned pointers can lead to a denial of service (bsc#1261894).\n- CVE-2026-34943: wasmtime: lifting `flags` component value can lead to a denial of service (bsc#1261954).\n- CVE-2026-34944: wasmtime: out-of-bounds read during WebAssembly compilation can lead to a denial of service\n  (bsc#1261963).\n- CVE-2026-34945: wasmtime: incorrectly translated table.size could lead to disclosing data (bsc#1262007).\n- CVE-2026-34946: wasmtime: denial of service due to WebAssembly compilation error (bsc#1261974).\n- CVE-2026-34987: wasmtime: winch compiler backend may allow a sandbox-escaping memory access (bsc#1262032).\n- CVE-2026-34988: wasmtime: pooling allocator instances can cause data leakage (bsc#1261968).\n- CVE-2026-35186: wasmtime: translating the table.grow operator can cause a masked return value (bsc#1262036).\n- CVE-2026-35195: wasmtime: transcoding strings can lead to an out of bound write or a crash (bsc#1262040).\n\nChanges for tree-sitter:\n\n- update to 0.26.8:\n\n * fix(generate): allow disabling qjs-rt feature from CLI by @WillLillis in\n #5448\n * fix(lib): document invariants that must be upheld for TSInputEdit by\n @WillLillis in #5452\n * fix(cli): correct typo in parse command's help text by @WillLillis in #5465\n * perf(cli): misc. improvements by @tree-sitter-ci-bot[bot] in #5476\n * Fix wasm loading of languages w/ multiple reserved word sets by\n @tree-sitter-ci-bot[bot] in #5477\n * generate: avoid panicking when a supertype only has hidden external token\n children by @tree-sitter-ci-bot[bot] in #5478\n","status":"published","published":"2026-05-14T08:09:11Z","modified":"2026-05-28T18:24:08.686123956Z","updated_at":"2026-11-02T15:54:02.654057Z"}]}}