{"id":"CVE-2026-115889","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-115889","generatedAt":"2026-10-28T01:02:39.545Z","title":"Prior to 36.0.19 and 43.0.0, the Cranelift compiler backend bit-packs SSA value indices in a way that can silently overflow in release builds when compiling a sufficiently large or specially crafted Wasm function with many SSA values.","description":"Wasmtime is a runtime for WebAssembly. Prior to 36.0.19 and 43.0.0, the Cranelift compiler backend bit-packs SSA value indices in a way that can silently overflow in release builds when compiling a sufficiently large or specially crafted Wasm function with many SSA values. The overflow can make Cranelift reference incorrect IR values, causing arbitrary miscompilation, type confusion, and other attacker-controlled effects that may escape the Wasm sandbox on any architecture using the default Cranelift backend. This issue is fixed in versions 36.0.19 and 43.0.0.","published":"2026-10-23T22:16:58.000Z","lastModified":"2026-10-26T18:17:38.000Z","status":"Deferred","sourceIdentifier":"security-advisories@github.com","cvss":{"version":"3.1","score":9.9,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H"},"cwe":["CWE-197","CWE-843"],"affected":[],"epss":{"score":0.00454,"percentile":0.39155,"date":"2026-10-26","history":[{"date":"2026-10-24","score":0.00663,"percentile":0.5115}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.45%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[{"kind":"new","label":"New CVE","at":"2026-10-23T22:16:58.000Z","detail":{"score":"9.9","severity":"CRITICAL","publishedAt":"2026-10-23T22:16:58.400Z"},"summary":"New CVE, critical severity (CVSS 9.9)."}],"references":[{"url":"https://github.com/bytecodealliance/wasmtime/commit/ba8f7d70caa1825b7f64fa75cd9d03f4a438dae0","source":"security-advisories@github.com"},{"url":"https://github.com/bytecodealliance/wasmtime/commit/f517bd6e890c7c1291ab9fe05d8cc0c9f11e56aa","source":"security-advisories@github.com"},{"url":"https://github.com/bytecodealliance/wasmtime/pull/12613","source":"security-advisories@github.com"},{"url":"https://github.com/bytecodealliance/wasmtime/pull/14818","source":"security-advisories@github.com"},{"url":"https://github.com/bytecodealliance/wasmtime/releases/tag/v36.0.19","source":"security-advisories@github.com"},{"url":"https://github.com/bytecodealliance/wasmtime/releases/tag/v43.0.0","source":"security-advisories@github.com"},{"url":"https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-897f-g5gm-fmxm","source":"security-advisories@github.com"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-115889","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}