{"id":"GHSA-jxhv-7h78-9775","summary":"Wasmtime: Panic when transcoding misaligned utf-16 strings","details":"### Impact\n\nWasmtime's implementation of transcoding strings into the Component Model's `utf16` or `latin1+utf16` encodings improperly verified the alignment of reallocated strings. This meant that unaligned pointers could be passed to the host for transcoding which would trigger a host panic. This panic is possible to trigger from malicious guests which transfer very specific strings across components with specific addresses. \n\nHost panics are considered a DoS vector in Wasmtime as the panic conditions are controlled by the guest in this situation.\n\n### Patches\n\nWasmtime 24.0.7, 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\nThere is no workaround for this bug. Hosts are recommended to updated to a patched version of Wasmtime.","aliases":["CVE-2026-34942","RUSTSEC-2026-0092"],"modified":"2026-07-17T21:07:06.607662129Z","published":"2026-04-09T20:22:12Z","database_specific":{"nvd_published_at":"2026-04-09T19:16:23Z","cwe_ids":["CWE-119","CWE-129"],"severity":"MODERATE","github_reviewed":true,"github_reviewed_at":"2026-04-09T20:22:12Z"},"references":[{"type":"WEB","url":"https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-jxhv-7h78-9775"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-34942"},{"type":"PACKAGE","url":"https://github.com/bytecodealliance/wasmtime"},{"type":"WEB","url":"https://rustsec.org/advisories/RUSTSEC-2026-0092.html"}],"affected":[{"package":{"name":"wasmtime","ecosystem":"crates.io","purl":"pkg:cargo/wasmtime"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"24.0.7"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/04/GHSA-jxhv-7h78-9775/GHSA-jxhv-7h78-9775.json"}},{"package":{"name":"wasmtime","ecosystem":"crates.io","purl":"pkg:cargo/wasmtime"},"ranges":[{"type":"SEMVER","events":[{"introduced":"25.0.0"},{"fixed":"36.0.7"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/04/GHSA-jxhv-7h78-9775/GHSA-jxhv-7h78-9775.json"}},{"package":{"name":"wasmtime","ecosystem":"crates.io","purl":"pkg:cargo/wasmtime"},"ranges":[{"type":"SEMVER","events":[{"introduced":"37.0.0"},{"fixed":"42.0.2"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/04/GHSA-jxhv-7h78-9775/GHSA-jxhv-7h78-9775.json"}},{"package":{"name":"wasmtime","ecosystem":"crates.io","purl":"pkg:cargo/wasmtime"},"ranges":[{"type":"SEMVER","events":[{"introduced":"43.0.0"},{"fixed":"43.0.1"}]}],"versions":["43.0.0"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/04/GHSA-jxhv-7h78-9775/GHSA-jxhv-7h78-9775.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"},{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L"}]}