{"id":"DEBIAN-CVE-2026-47261","details":"Wasmtime is a runtime for WebAssembly. In versions prior to 24.0.9, 36.0.10, and 44.0.2, when a filesystem preopen is given DirPerms::all() and FilePerms::READ without FilePerms::WRITE, this access control mechanism can be bypassed via the wasip2 descriptor.open-at or wasip1 path_open interfaces by opening a file with only the OpenFlags::TRUNCATE oflag. The root cause is that the clause handling OpenFlags::TRUNCATE in crates/wasi/src/filesystem.rs (Dir::open_at, lines 967–969) did not set open_mode |= OpenMode::WRITE;, which is later used for the access control check against FilePerms to determine whether opening the file is permitted; the single-line fix adds that missing assignment, after which the affected calls correctly fail with error-code.not-permitted and ERRNO_PERM respectively. Only wasmtime-wasi embeddings that combine DirPerms::MUTATE with FilePerms::READ are affected by this bug. In particular, the Wasmtime project's wasmtime-cli's use of wasmtime-wasi is not affected, because it always sets FilePerms::all() for all preopens. This issue has been fixed in versions 24.0.9, 36.0.10 and44.0.2.","modified":"2026-09-14T17:03:41.384624335Z","published":"2026-06-15T21:17:11.153Z","upstream":["CVE-2026-47261"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-47261"}],"affected":[{"package":{"name":"rust-wasmtime","ecosystem":"Debian:13","purl":"pkg:deb/debian/rust-wasmtime?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["26.0.1+dfsg-10","26.0.1+dfsg-3","26.0.1+dfsg-4","26.0.1+dfsg-5","26.0.1+dfsg-6","26.0.1+dfsg-7","26.0.1+dfsg-8","26.0.1+dfsg-9","27.0.0+dfsg-2","27.0.0+dfsg-3","27.0.0+dfsg-4","28.0.1+dfsg-1","28.0.1+dfsg-2","28.0.1+dfsg-3","29.0.1+dfsg-1","29.0.1+dfsg-2","29.0.1+dfsg-3","29.0.1+dfsg-4","29.0.1+dfsg-5","29.0.1+dfsg-6","29.0.1+dfsg-7","29.0.1+dfsg-8","36.0.11+dfsg-1","36.0.12+dfsg-1","36.0.12+dfsg-2","36.0.12+dfsg-3","36.0.13+dfsg-1","36.0.5+dfsg-1","36.0.5+dfsg-2","36.0.5+dfsg-3","36.0.5+dfsg-4","36.0.5+dfsg-5","36.0.6+dfsg-1","36.0.6+dfsg-2","36.0.6+dfsg-3","36.0.6+dfsg-4","36.0.6+dfsg-5","36.0.6+dfsg-6","36.0.6+dfsg-7","36.0.7+dfsg-1","36.0.8+dfsg-1","36.0.9+dfsg-1","36.0.9+dfsg-2"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-47261.json"}},{"package":{"name":"rust-wasmtime","ecosystem":"Debian:14","purl":"pkg:deb/debian/rust-wasmtime?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"36.0.11+dfsg-1"}]}],"versions":["26.0.1+dfsg-10","26.0.1+dfsg-3","26.0.1+dfsg-4","26.0.1+dfsg-5","26.0.1+dfsg-6","26.0.1+dfsg-7","26.0.1+dfsg-8","26.0.1+dfsg-9","27.0.0+dfsg-2","27.0.0+dfsg-3","27.0.0+dfsg-4","28.0.1+dfsg-1","28.0.1+dfsg-2","28.0.1+dfsg-3","29.0.1+dfsg-1","29.0.1+dfsg-2","29.0.1+dfsg-3","29.0.1+dfsg-4","29.0.1+dfsg-5","29.0.1+dfsg-6","29.0.1+dfsg-7","29.0.1+dfsg-8","36.0.5+dfsg-1","36.0.5+dfsg-2","36.0.5+dfsg-3","36.0.5+dfsg-4","36.0.5+dfsg-5","36.0.6+dfsg-1","36.0.6+dfsg-2","36.0.6+dfsg-3","36.0.6+dfsg-4","36.0.6+dfsg-5","36.0.6+dfsg-6","36.0.6+dfsg-7","36.0.7+dfsg-1","36.0.8+dfsg-1","36.0.9+dfsg-1","36.0.9+dfsg-2"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-47261.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"}]}