{"id":"GHSA-m9w2-8782-2946","revision":"0da012cf6cf84030863af7632b0940c9","records":[{"revision":"0da012cf6cf84030863af7632b0940c9","observedAt":"2026-10-24T13:19:54.901+00:00","statement":{"source":"osv","id":"GHSA-m9w2-8782-2946","aliases":["CVE-2026-34945","RUSTSEC-2026-0086"],"title":"Wasmtime has host data leakage with 64-bit tables and Winch","description":"### Impact\n\nWasmtime'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.\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":[]}],"coverage":[]}