CVE-2026-47261

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.
Configurations

Configuration 1 (hide)

OR cpe:2.3:a:bytecodealliance:wasmtime:*:*:*:*:*:rust:*:*
cpe:2.3:a:bytecodealliance:wasmtime:*:*:*:*:*:rust:*:*
cpe:2.3:a:bytecodealliance:wasmtime:*:*:*:*:*:rust:*:*

History

17 Jun 2026, 16:42

Type Values Removed Values Added
References () https://github.com/bytecodealliance/wasmtime/releases/tag/v24.0.9 - () https://github.com/bytecodealliance/wasmtime/releases/tag/v24.0.9 - Release Notes
References () https://github.com/bytecodealliance/wasmtime/releases/tag/v36.0.10 - () https://github.com/bytecodealliance/wasmtime/releases/tag/v36.0.10 - Release Notes
References () https://github.com/bytecodealliance/wasmtime/releases/tag/v44.0.2 - () https://github.com/bytecodealliance/wasmtime/releases/tag/v44.0.2 - Release Notes
References () https://github.com/bytecodealliance/wasmtime/releases/tag/v45.0.0 - () https://github.com/bytecodealliance/wasmtime/releases/tag/v45.0.0 - Release Notes
References () https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-2r75-cxrj-cmph - () https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-2r75-cxrj-cmph - Mitigation, Vendor Advisory
CPE cpe:2.3:a:bytecodealliance:wasmtime:*:*:*:*:*:rust:*:*
First Time Bytecodealliance
Bytecodealliance wasmtime
CWE NVD-CWE-noinfo

15 Jun 2026, 21:17

Type Values Removed Values Added
New CVE

Information

Published : 2026-06-15 21:17

Updated : 2026-06-17 16:42


NVD link : CVE-2026-47261

Mitre link : CVE-2026-47261

CVE.ORG link : CVE-2026-47261


JSON object : View

Products Affected

bytecodealliance

  • wasmtime
CWE
CWE-284

Improper Access Control

NVD-CWE-noinfo