{"id":"CVE-2026-121440","aliases":["EUVD-2026-115862","GHSA-j86m-34pm-p9mv","GHSA-jxcf-8qw5-5c33","RUSTSEC-2026-0377"],"status":"published","title":"Wasmtime 46.0.0 before 48.0.7 and 49.0.0 before 49.0.4 Forwarded Trailers Header Filter Bypass","description":"Wasmtime 46.0.0 before 48.0.7 and 49.0.0 before 49.0.4 fails to check forwarded trailers against the WasiHttpHooks::is_forbidden_header hook in wasi-http p3. WASIp3 guests can forward a request or response body so its trailers skip embedder-customized forbidden header filtering, undermining header restrictions the embedder intended.","severity":{"version":"4.0","score":6.3,"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00224,"percentile":0.13183,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-424"],"published":"2026-10-19T12:00:00Z","modified":"2026-11-04T02:47:30Z","fixes":[{"ecosystem":"crates.io","package":"wasmtime-wasi-http","fixed_in":["48.0.7","49.0.4"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"crates.io","package":"wasmtime-wasi-http","ranges":[{"type":"SEMVER","events":[{"introduced":"46.0.0"},{"fixed":"48.0.7"},{"introduced":"49.0.0"},{"fixed":"49.0.4"}]}]}],"products":[{"vendor":"bytecodealliance","product":"wasmtime"}],"references":[{"url":"https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-jxcf-8qw5-5c33","tags":["vendor-advisory","advisory"]},{"url":"https://www.vulncheck.com/advisories/wasmtime-46.0.0-before-48.0.7-and-49.0.0-before-49.0.4-forwarded-trailers-header-filter-bypass","tags":["third-party-advisory","advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-121440","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-j86m-34pm-p9mv"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/121xxx/CVE-2026-121440.json","tags":["advisory"]},{"url":"https://crates.io/crates/wasmtime-wasi-http","tags":["package"]},{"url":"https://rustsec.org/advisories/RUSTSEC-2026-0377.html","tags":["advisory"]},{"url":"https://github.com/bytecodealliance/wasmtime/pull/14823","tags":["web"]}],"sources":{"cve":[{"id":"CVE-2026-121440","title":"Wasmtime 46.0.0 before 48.0.7 and 49.0.0 before 49.0.4 Forwarded Trailers Header Filter Bypass","description":"Wasmtime 46.0.0 before 48.0.7 and 49.0.0 before 49.0.4 fails to check forwarded trailers against the WasiHttpHooks::is_forbidden_header hook in wasi-http p3. WASIp3 guests can forward a request or response body so its trailers skip embedder-customized forbidden header filtering, undermining header restrictions the embedder intended.","status":"published","published":"2026-11-03T14:28:31.228Z","modified":"2026-11-03T18:28:48.629Z","cvss":[{"version":"4.0","score":6.3,"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N","level":"medium","assessor":"cna"},{"version":"3.1","score":3.7,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"low","assessor":"cna"}],"cwes":["CWE-424"],"updated_at":"2026-11-03T20:02:16.924578Z"}],"euvd":[{"id":"EUVD-2026-115862","description":"Wasmtime 46.0.0 before 48.0.7 and 49.0.0 before 49.0.4 fails to check forwarded trailers against the WasiHttpHooks::is_forbidden_header hook in wasi-http p3. WASIp3 guests can forward a request or response body so its trailers skip embedder-customized forbidden header filtering, undermining header restrictions the embedder intended.","status":"published","published":"2026-11-03T14:28:31Z","modified":"2026-11-03T18:28:48Z","cvss":[{"version":"4.0","score":6.3,"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N","level":"medium"}],"updated_at":"2026-11-03T20:20:09.141953Z"}],"ghsa":[{"id":"GHSA-j86m-34pm-p9mv","title":"Wasmtime 46.0.0 before 48.0.7 and 49.0.0 before 49.0.4 fails to check forwarded trailers against...","description":"Wasmtime 46.0.0 before 48.0.7 and 49.0.0 before 49.0.4 fails to check forwarded trailers against the WasiHttpHooks::is_forbidden_header hook in wasi-http p3. WASIp3 guests can forward a request or response body so its trailers skip embedder-customized forbidden header filtering, undermining header restrictions the embedder intended.","status":"published","published":"2026-11-03T15:32:18Z","modified":"2026-11-03T15:32:18Z","cvss":[{"version":"4.0","score":6.3,"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/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"},{"version":"3.1","score":3.7,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"low"}],"cwes":["CWE-424"],"updated_at":"2026-11-03T15:57:23.404697Z"}],"nvd":[{"id":"CVE-2026-121440","description":"Wasmtime 46.0.0 before 48.0.7 and 49.0.0 before 49.0.4 fails to check forwarded trailers against the WasiHttpHooks::is_forbidden_header hook in wasi-http p3. WASIp3 guests can forward a request or response body so its trailers skip embedder-customized forbidden header filtering, undermining header restrictions the embedder intended.","status":"published","published":"2026-11-03T15:17:35.707Z","modified":"2026-11-03T19:18:03.383Z","cvss":[{"version":"4.0","score":6.3,"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/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":3.7,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"low","assessor":"secondary"}],"cwes":["CWE-424"],"updated_at":"2026-11-03T22:58:51.822037Z"}],"osv":[{"id":"CVE-2026-121440","title":"Wasmtime 46.0.0 before 48.0.7 and 49.0.0 before 49.0.4 Forwarded Trailers Header Filter Bypass","description":"Wasmtime 46.0.0 before 48.0.7 and 49.0.0 before 49.0.4 fails to check forwarded trailers against the WasiHttpHooks::is_forbidden_header hook in wasi-http p3. WASIp3 guests can forward a request or response body so its trailers skip embedder-customized forbidden header filtering, undermining header restrictions the embedder intended.","status":"published","published":"2026-11-03T14:28:31.228Z","modified":"2026-11-05T02:30:34.509938606Z","cvss":[{"version":"4.0","score":6.3,"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N","level":"medium"}],"cwes":["CWE-424"],"updated_at":"2026-11-07T03:08:01.726202Z"},{"id":"RUSTSEC-2026-0377","title":"`wasi-http` p3: forwarded trailers aren't checked against `is_forbidden_header` hook","description":"This is an entry in the RustSec database for the Wasmtime security advisory\nlocated at\nhttps://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-jxcf-8qw5-5c33\nFor more information see the GitHub-hosted security advisory.","status":"published","published":"2026-10-19T12:00:00Z","modified":"2026-11-04T02:55:58.676339211Z","cvss":[{"version":"3.1","score":3.7,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"low"}],"updated_at":"2026-11-04T03:25:28.514393Z"}]}}