CVE-2026-115889

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{"affected": [{"affectedData": [{"product": "wasmtime", "vendor": "bytecodealliance", "versions": [{"status": "affected", "version": "< 36.0.19"}, {"status": "affected", "version": ">= 37.0.0, < 43.0.0"}]}], "source": "security-advisories@github.com"}], "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."}], "id": "CVE-2026-115889", "lastModified": "2026-10-26T18:17:38.213", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 9.9, "baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "CHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 3.1, "impactScore": 6.0, "source": "security-advisories@github.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-115889", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-10-26T15:40:36.390562Z", "version": "2.0.3"}}]}, "published": "2026-10-23T22:16:58.400", "references": [{"source": "security-advisories@github.com", "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"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Deferred", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-197"}, {"lang": "en", "value": "CWE-843"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{"bugzilla": {"description": "wasmtime: Wasmtime: Bit-packing in Cranelift compiler causes silent overflow and miscompilation", "id": "2560221", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2560221"}, "csaw": false, "cvss3": {"cvss3_base_score": "8.8", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H", "status": "draft"}, "cwe": "CWE-190", "details": ["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.", "A flaw was found in Wasmtime. An attacker could achieve a sandbox escape and compromise the host system by supplying a specially crafted WebAssembly (Wasm) module. When compiling functions containing an unusually large number of internal values, an integer overflow in the Cranelift compiler backend can cause incorrect code generation and type confusion. This miscompilation allows untrusted guest code to break out of the secure execution environment."], "mitigation": {"lang": "en:us", "value": "Restrict execution to trusted WebAssembly modules and avoid processing unvalidated binaries from untrusted sources. If the runtime must process untrusted modules, deploy the hosting application inside an operating system-level sandbox or container (such as Podman or a systemd service unit configured with strict seccomp filtering, unprivileged user namespaces, and read-only filesystem mounts) to contain a potential sandbox breakout.\nCaveats: Additional host-level sandboxing introduces operational overhead and may restrict legitimate host system interactions or inter-process communication required by the guest application."}, "name": "CVE-2026-115889", "package_state": [{"cpe": "cpe:/a:redhat:connectivity_link:1", "fix_state": "Affected", "package_name": "rhcl-1/wasm-shim-rhel9", "product_name": "Red Hat Connectivity Link 1"}, {"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "tree-sitter", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "virt-firmware-rs", "product_name": "Red Hat Enterprise Linux 10"}], "public_date": "2026-10-23T21:23:27Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-115889\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-115889\nhttps://github.com/bytecodealliance/wasmtime/commit/ba8f7d70caa1825b7f64fa75cd9d03f4a438dae0\nhttps://github.com/bytecodealliance/wasmtime/commit/f517bd6e890c7c1291ab9fe05d8cc0c9f11e56aa\nhttps://github.com/bytecodealliance/wasmtime/pull/12613\nhttps://github.com/bytecodealliance/wasmtime/pull/14818\nhttps://github.com/bytecodealliance/wasmtime/releases/tag/v36.0.19\nhttps://github.com/bytecodealliance/wasmtime/releases/tag/v43.0.0\nhttps://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-897f-g5gm-fmxm"], "statement": "This vulnerability is rated as Important severity because an untrusted guest WebAssembly payload can break sandbox boundaries and gain full host system access. While triggering the issue requires supplying an extraordinarily complex or specially structured module, the ability to achieve sandbox breakout without administrative privileges warrants an Important rating. In Red Hat environments, the primary risk lies in multi-tenant or serverless hosting configurations where untrusted WebAssembly binaries are accepted and executed.", "threat_severity": "Important"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,36.0.19)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[37.0.0,43.0.0)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "wasmtime", "source": "cna", "vendor": "bytecodealliance"}, "product": "wasmtime", "vendor": "bytecodealliance"}], "created": "2026-10-23T22:30:14.519027+00:00", "updated": "2026-10-29T14:15:07.596832+00:00", "vendors": ["bytecodealliance", "bytecodealliance$PRODUCT$wasmtime"]}