{"id":"CVE-2026-126406","summary":"Wasmtime before 36.0.20 HTTP Request Smuggling via wasi-http p2 Content-Length","details":"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.","aliases":["GHSA-h4wp-g4x3-7398","RUSTSEC-2026-0421"],"modified":"2026-11-15T02:31:04.340626894Z","published":"2026-11-13T09:35:44.314Z","database_specific":{"cwe_ids":["CWE-444"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/126xxx/CVE-2026-126406.json","cna_assigner":"VulnCheck"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/126xxx/CVE-2026-126406.json"},{"type":"ADVISORY","url":"https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-h4wp-g4x3-7398"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-126406"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/wasmtime-before-36.0.20-http-request-smuggling-via-wasi-http-p2-content-length"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/bytecodealliance/wasmtime","events":[{"introduced":"0"},{"fixed":"b265f78b1e92e12240ec7bdc21c7a559d2df968e"},{"introduced":"7b3d6ae79e9153a2477668062f5622c10333925f"},{"fixed":"7b6c29ec3e9a49c97da231665cbd8eead9ccbda0"},{"introduced":"17830bd3c0331d920a8aa38846eebc4d46d98c23"},{"fixed":"805a0f15320e8836cf2b9f001b53d884bf866c89"},{"introduced":"ebe5e8df1f4e12c5fc2f5954926881d8d61367d8"},{"fixed":"c307ec81de02852d815e9849f7c89d955c03c30d"}],"database_specific":{"extracted_events":[{"source":"AFFECTED_FIELD","strategy":"StandardRange","range":[{"introduced":"0"},{"fixed":"36.0.20"}]},{"range":[{"introduced":"37.0.0"},{"fixed":"48.0.8"}],"source":"AFFECTED_FIELD","strategy":"StandardRange"},{"range":[{"introduced":"49.0.0"},{"fixed":"49.0.5"}],"source":"AFFECTED_FIELD","strategy":"StandardRange"},{"range":[{"introduced":"50.0.0"},{"fixed":"50.0.1"}],"source":"AFFECTED_FIELD","strategy":"StandardRange"}]}}],"versions":["v50.0.0","v49.0.4","v36.0.19","v48.0.7","v36.0.18","v48.0.6","v49.0.3","v48.0.5","v36.0.17","v49.0.2","v48.0.4","v48.0.3","v49.0.1","v36.0.16","v49.0.0","v48.0.2","v36.0.15","v48.0.1","v36.0.14","v48.0.0","v36.0.13","v36.0.12","v36.0.11","v36.0.10","v36.0.9","v36.0.8","v36.0.7","v36.0.6","v36.0.5","v36.0.4","v36.0.3","v36.0.2","v36.0.1","v36.0.0","v0.35.0","v0.33.0","v0.34.0","v0.32.0","v0.31.0","v0.30.0","v0.29.0","v0.28.0","v0.27.0","v0.26.0","v0.25.0","v0.24.0","v0.23.0","v0.22.0","cranelift-v0.69.0","v0.21.0","v0.20.0","v0.19.0","v0.18.0","v0.17.0","v0.16.0","cranelift-v0.61.0","cranelift-v0.60.0","v0.12.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-126406.json"}}],"schema_version":"1.9.2","severity":[{"type":"CVSS_V4","score":"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"}]}