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Improper Access Control Affecting rust-wasmtime package, versions *

Severity

 Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.5% (39th percentile)

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  • Snyk IDSNYK-DEBIAN14-RUSTWASMTIME-17345970
  • published16 Jun 2026
  • disclosed15 Jun 2026
Report a new vulnerability Found a mistake?

Introduced: 15 Jun 2026

NewCVE-2026-47261  (opens in a new tab)
CWE-284  (opens in a new tab)

How to fix?

There is no fixed version for Debian:14 rust-wasmtime.

NVD Description

Note: Versions mentioned in the description apply only to the upstream rust-wasmtime package and not the rust-wasmtime package as distributed by Debian. See How to fix? for Debian:14 relevant fixed versions and status.

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.