{"id":"CVE-2026-126406","aliases":["EUVD-2026-125159","GHSA-h4wp-g4x3-7398","GHSA-xhgr-wvjp-62fm","RUSTSEC-2026-0421","UBUNTU-CVE-2026-126406"],"status":"published","title":"Wasmtime before 36.0.20 HTTP Request Smuggling via wasi-http p2 Content-Length","description":"The wasmtime-wasi-http p2 implementation in Wasmtime before 36.0.20, 37.0.0 before 48.0.8, 49.0.0 before 49.0.5, and 50.0.0 before 50.0.1 can send conflicting content-length headers, or ones not matching the body, in outgoing requests. A guest that reuses a received response's headers resource to send a bodyless request can enable request smuggling against non-compliant servers, potentially bypassing embedder destination access controls.","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":"2026-11-13","score":0.00319,"percentile":0.2517,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-444"],"published":"2026-10-29T12:00:00Z","modified":"2026-11-14T02:56:01Z","fixes":[{"ecosystem":"crates.io","package":"wasmtime-wasi-http","fixed_in":["36.0.20","48.0.8","49.0.5","50.0.1"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"crates.io","package":"wasmtime-wasi-http","ranges":[{"type":"SEMVER","events":[{"introduced":"0.0.0-0"},{"fixed":"36.0.20"},{"introduced":"37.0.0"},{"fixed":"48.0.8"},{"introduced":"49.0.0"},{"fixed":"49.0.5"},{"introduced":"50.0.0"},{"fixed":"50.0.1"}]}]},{"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: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"]}],"products":[{"vendor":"bytecodealliance","product":"wasmtime"}],"references":[{"url":"https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-h4wp-g4x3-7398","tags":["vendor-advisory","advisory","report"]},{"url":"https://www.vulncheck.com/advisories/wasmtime-before-36.0.20-http-request-smuggling-via-wasi-http-p2-content-length","tags":["third-party-advisory","advisory","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-126406","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-xhgr-wvjp-62fm"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/126xxx/CVE-2026-126406.json","tags":["advisory"]},{"url":"https://crates.io/crates/wasmtime-wasi-http","tags":["package"]},{"url":"https://rustsec.org/advisories/RUSTSEC-2026-0421.html","tags":["advisory"]},{"url":"https://github.com/bytecodealliance/wasmtime/pull/15070","tags":["web"]},{"url":"https://ubuntu.com/security/CVE-2026-126406","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-126406","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-126406","title":"Wasmtime before 36.0.20 HTTP Request Smuggling via wasi-http p2 Content-Length","description":"The wasmtime-wasi-http p2 implementation in Wasmtime before 36.0.20, 37.0.0 before 48.0.8, 49.0.0 before 49.0.5, and 50.0.0 before 50.0.1 can send conflicting content-length headers, or ones not matching the body, in outgoing requests. A guest that reuses a received response's headers resource to send a bodyless request can enable request smuggling against non-compliant servers, potentially bypassing embedder destination access controls.","status":"published","published":"2026-11-13T09:35:44.314Z","modified":"2026-11-13T09:35:44.314Z","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-444"],"updated_at":"2026-11-13T10:27:12.184616Z"}],"euvd":[{"id":"EUVD-2026-125159","description":"The wasmtime-wasi-http p2 implementation in Wasmtime before 36.0.20, 37.0.0 before 48.0.8, 49.0.0 before 49.0.5, and 50.0.0 before 50.0.1 can send conflicting content-length headers, or ones not matching the body, in outgoing requests. A guest that reuses a received response's headers resource to send a bodyless request can enable request smuggling against non-compliant servers, potentially bypassing embedder destination access controls.","status":"published","published":"2026-11-13T09:35:44Z","modified":"2026-11-13T09:35:44Z","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":"2026-11-13T14:38:51.723487Z"}],"ghsa":[{"id":"GHSA-xhgr-wvjp-62fm","title":"The wasmtime-wasi-http p2 implementation in Wasmtime before 36.0.20, 37.0.0 before 48.0.8, 49.0.0...","description":"The wasmtime-wasi-http p2 implementation in Wasmtime before 36.0.20, 37.0.0 before 48.0.8, 49.0.0 before 49.0.5, and 50.0.0 before 50.0.1 can send conflicting content-length headers, or ones not matching the body, in outgoing requests. A guest that reuses a received response's headers resource to send a bodyless request can enable request smuggling against non-compliant servers, potentially bypassing embedder destination access controls.","status":"published","published":"2026-11-13T12:31:22Z","modified":"2026-11-13T12:31:28Z","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-444"],"updated_at":"2026-11-13T12:50:13.746549Z"}],"nvd":[{"id":"CVE-2026-126406","description":"The wasmtime-wasi-http p2 implementation in Wasmtime before 36.0.20, 37.0.0 before 48.0.8, 49.0.0 before 49.0.5, and 50.0.0 before 50.0.1 can send conflicting content-length headers, or ones not matching the body, in outgoing requests. A guest that reuses a received response's headers resource to send a bodyless request can enable request smuggling against non-compliant servers, potentially bypassing embedder destination access controls.","status":"published","published":"2026-11-13T10:17:45.44Z","modified":"2026-11-13T10:17:45.583Z","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":"primary"}],"cwes":["CWE-444"],"updated_at":"2026-11-13T11:35:38.52146Z"}],"osv":[{"id":"CVE-2026-126406","title":"Wasmtime before 36.0.20 HTTP Request Smuggling via wasi-http p2 Content-Length","description":"The wasmtime-wasi-http p2 implementation in Wasmtime before 36.0.20, 37.0.0 before 48.0.8, 49.0.0 before 49.0.5, and 50.0.0 before 50.0.1 can send conflicting content-length headers, or ones not matching the body, in outgoing requests. A guest that reuses a received response's headers resource to send a bodyless request can enable request smuggling against non-compliant servers, potentially bypassing embedder destination access controls.","status":"published","published":"2026-11-13T09:35:44.314Z","modified":"2026-11-14T02:56:01.975102982Z","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-444"],"updated_at":"2026-11-14T03:11:06.681237Z"},{"id":"RUSTSEC-2026-0421","title":"wasi-http p2: outgoing content-length can be invalid or not match body","description":"This is an entry in the RustSec database for the Wasmtime security advisory\nlocated at\nhttps://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-h4wp-g4x3-7398\nFor more information see the GitHub-hosted security advisory.","status":"published","published":"2026-10-29T12:00:00Z","modified":"2026-11-14T02:56:01.975102982Z","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":"2026-11-14T03:11:06.681237Z"},{"id":"UBUNTU-CVE-2026-126406","description":"The wasmtime-wasi-http p2 implementation in Wasmtime before 36.0.20, 37.0.0 before 48.0.8, 49.0.0 before 49.0.5, and 50.0.0 before 50.0.1 can send conflicting content-length headers, or ones not matching the body, in outgoing requests. A guest that reuses a received response's headers resource to send a bodyless request can enable request smuggling against non-compliant servers, potentially bypassing embedder destination access controls.","status":"published","published":"2026-11-13T00:00:00Z","modified":"2026-11-13T21:05:26.408157475Z","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"},{"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":"2026-11-13T21:30:20.292037Z"}]}}