Wasmtime: WASI path_open(TRUNCATE) bypasses `FilePerms::WRITE` host restriction
Summary
| CVE | CVE-2026-47261 |
|---|---|
| State | PUBLISHED |
| Assigner | GitHub_M |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-06-15 21:17:11 UTC |
| Updated | 2026-06-17 16:42:08 UTC |
| Description | 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. |
Risk And Classification
Primary CVSS: v3.1 7.5 HIGH from [email protected]
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
EPSS: 0.005000000 probability, percentile 0.387600000 (date 2026-06-21)
Problem Types: CWE-284 | NVD-CWE-noinfo | CWE-284 CWE-284: Improper Access Control
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | [email protected] | Secondary | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N |
| 3.1 | CNA | DECLARED | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N |
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
LowPrivileges Required
NoneUser Interaction
NoneScope
UnchangedConfidentiality
NoneIntegrity
HighAvailability
NoneCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
NVD Known Affected Configurations (CPE 2.3)
| Type | Vendor | Product | Version | Update | Edition | Language |
|---|---|---|---|---|---|---|
| Application | Bytecodealliance | Wasmtime | All | All | All | All |
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Bytecodealliance | Wasmtime | affected >= 37.0.0, < 44.0.2 | Not specified |
| CNA | Bytecodealliance | Wasmtime | affected >= 25.0.0, < 36.0.10 | Not specified |
| CNA | Bytecodealliance | Wasmtime | affected < 24.0.9 | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/bytecodealliance/wasmtime/releases/tag/v24.0.9 | [email protected] | github.com | Release Notes |
| github.com/bytecodealliance/wasmtime/releases/tag/v44.0.2 | [email protected] | github.com | Release Notes |
| github.com/bytecodealliance/wasmtime/security/advisories/GHSA-2r75-cxrj-... | [email protected] | github.com | Mitigation, Vendor Advisory |
| github.com/bytecodealliance/wasmtime/releases/tag/v45.0.0 | [email protected] | github.com | Release Notes |
| github.com/bytecodealliance/wasmtime/releases/tag/v36.0.10 | [email protected] | github.com | Release Notes |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.