{"id":"CVE-2026-115889","sourceIdentifier":"security-advisories@github.com","published":"2026-10-23T22:16:58.400","lastModified":"2026-10-23T22:16:58.550","vulnStatus":"Deferred","cveTags":[],"descriptions":[{"lang":"en","value":"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."}],"affected":[{"source":"security-advisories@github.com","affectedData":[{"vendor":"bytecodealliance","product":"wasmtime","versions":[{"version":"< 36.0.19","status":"affected"},{"version":">= 37.0.0, < 43.0.0","status":"affected"}]}]}],"metrics":{"cvssMetricV31":[{"source":"security-advisories@github.com","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","baseScore":9.9,"baseSeverity":"CRITICAL","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"CHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":3.1,"impactScore":6.0}]},"weaknesses":[{"source":"security-advisories@github.com","type":"Primary","description":[{"lang":"en","value":"CWE-197"},{"lang":"en","value":"CWE-843"}]}],"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"}]}