{"id":"CVE-2026-34945","revision":null,"records":[{"revision":"8b32686bc75c4c52a6f86abbb05ad038","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-34945","aliases":[],"title":"Wasmtime leaks host data with 64-bit tables and Winch","description":"Wasmtime is a runtime for WebAssembly. From 25.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime's Winch compiler contains a bug where a 64-bit table, part of the memory64 proposal of WebAssembly, incorrectly translated the table.size instruction. This bug could lead to disclosing data on the host's stack to WebAssembly guests. The host's stack can possibly contain sensitive data related to other host-originating operations which is not intended to be disclosed to guests. This bug specifically arose from a mistake where the return value of table.size was statically typed as a 32-bit integer, as opposed to consulting the table's index type to see how large the returned register could be. When combined with details about Wnich's ABI, such as multi-value returns, this can be combined to read stack data from the host, within a guest. 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When combined with details about Wnich's ABI, such as multi-value returns, this can be combined to read stack data from the host, within a guest. 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Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON."},"key":"euvd:EUVD-2026-21024","identifiers":["EUVD-2026-21024","CVE-2026-34945","GHSA-m9w2-8782-2946"]},"retained":false,"historicalAffected":[]},{"revision":"cb0e931364ab4bb2bacdbdda670723c2","observedAt":"2026-10-27T09:03:08.102+00:00","statement":{"source":"nvd","id":"CVE-2026-34945","aliases":[],"title":"Wasmtime is a runtime for WebAssembly. From 25.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime's Winch compiler contains a bug where a 64-bit table, part of the memory64 proposal of WebAssembly, incorrectly translated the table.size inst…","description":"Wasmtime is a runtime for WebAssembly. 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The host's stack can possibly contain sensitive data related to other host-originating operations which is not intended to be disclosed to guests.\n\nThis bug specifically arose from a mistake where the return value of `table.size` was statically typed as a 32-bit integer, as opposed to consulting the table's index type to see how large the returned register could be. When combined with details about Wnich's ABI, such as multi-value returns, this can be combined to read stack data from the host, within a guest. This information disclosure should not be possible in WebAssembly, violates spec semantics, and is a vulnerability in Wasmtime.\n\n### Patches\n\nWasmtime 36.0.7, 42.0.2, and 43.0.1 have been issued to fix this bug. Users are recommended to update to these patched versions of Wasmtime.\n\n### Workarounds\n\nUsers of Cranelift are not affected by this issue, but users of Winch have no workarounds other than disabling the `Config::wasm_memory64` proposal.","state":0,"publishedAt":"2026-04-09T20:23:02+00:00","modifiedAt":"2026-09-10T03:51:02.3092753+00:00","affected":[{"ecosystem":"crates.io","name":"wasmtime","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"25.0.0"},{"kind":"fixed","version":"36.0.7"}]}],"versions":[],"rawVersionEvidence":null},{"ecosystem":"crates.io","name":"wasmtime","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"37.0.0"},{"kind":"fixed","version":"42.0.2"}]}],"versions":[],"rawVersionEvidence":null},{"ecosystem":"crates.io","name":"wasmtime","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"43.0.0"},{"kind":"fixed","version":"43.0.1"}]}],"versions":["43.0.0"],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V3","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N","score":null,"severity":null},{"system":"CVSS_V4","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"LOW"}],"references":["https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-m9w2-8782-2946","https://nvd.nist.gov/vuln/detail/CVE-2026-34945","https://github.com/bytecodealliance/wasmtime","https://rustsec.org/advisories/RUSTSEC-2026-0086.html"],"sourceUrl":"https://github.com/advisories/GHSA-m9w2-8782-2946","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-m9w2-8782-2946","identifiers":["GHSA-m9w2-8782-2946","CVE-2026-34945","RUSTSEC-2026-0086"]},"retained":false,"historicalAffected":[]},{"revision":"141cba7b7dd5463db682f34a6b7bc39d","observedAt":"2026-10-24T13:19:54.901+00:00","statement":{"source":"osv","id":"RUSTSEC-2026-0086","aliases":["CVE-2026-34945","GHSA-m9w2-8782-2946"],"title":"Host data leakage with 64-bit tables and Winch","description":"This is an entry in the RustSec database for the Wasmtime security advisory\nlocated at\nhttps://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-m9w2-8782-2946\nFor more information see the GitHub-hosted security advisory.","state":0,"publishedAt":"2026-04-09T12:00:00+00:00","modifiedAt":"2026-10-12T18:00:09.9307987+00:00","affected":[{"ecosystem":"crates.io","name":"wasmtime","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0.0.0-0"},{"kind":"fixed","version":"36.0.7"},{"kind":"introduced","version":"37.0.0"},{"kind":"fixed","version":"42.0.2"},{"kind":"introduced","version":"43.0.0"},{"kind":"fixed","version":"43.0.1"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V4","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N","score":null,"severity":null}],"references":["https://crates.io/crates/wasmtime","https://rustsec.org/advisories/RUSTSEC-2026-0086.html","https://github.com/bytecodealliance/wasmtime/pull/13009"],"sourceUrl":"https://osv.dev/vulnerability/RUSTSEC-2026-0086","license":"OSV · upstream source license applies","key":"osv:RUSTSEC-2026-0086","identifiers":["RUSTSEC-2026-0086","CVE-2026-34945","GHSA-m9w2-8782-2946"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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