cve.bz

CVE-2026-47261

7.5 highEPSS 0.4%

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.

CVSS 3.1
7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
EPSS
0.4% chance of exploitation in the next 30 days; higher than 29% of CVEs (scores of 2026-10-25)
CWE
CWE-284
Published
Modified
Record from
the NVD, synced

Affected

Packages (OSV)

AdvisoryEcosystemPackageAffectedFixed in
GHSA-2r75-cxrj-cmphcrates.iowasmtime-wasi>=37.0.0 <44.0.244.0.2
GHSA-2r75-cxrj-cmphcrates.iowasmtime-wasi>=25.0.0 <36.0.1036.0.10
GHSA-2r75-cxrj-cmphcrates.iowasmtime-wasi<24.0.924.0.9
RUSTSEC-2026-0149crates.iowasmtime-wasi>=0.0.0-0 <24.0.9
>=25.0.0 <36.0.10
>=37.0.0 <44.0.2
>=45.0.0 <45.0.0		24.0.9, 36.0.10, 44.0.2, 45.0.0

References

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