Skip to content
Patch Next
Sign inAdd to your agent

← Actionable
High, CVSS 7.5

wasmtime-wasi: WASI path_open(TRUNCATE) bypasses FilePerms::WRITE host restriction

CVE-2026-47261GHSA-2r75-cxrj-cmph

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (wasmtime-wasi 44.0.2, 36.0.10, 24.0.9), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

Add to your agent

Affected packages

  • crates.io wasmtime-wasi

    Affected
    >= 37.0.0, < 44.0.2>= 25.0.0, < 36.0.10< 24.0.9
    Fixed in
    44.0.2, 36.0.10, 24.0.9

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
EPSS
  • CVE-2026-47261: 0.36% estimated exploitation activity in the next 30 days; percentile 29.51 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary In wasmtime-wasi, when a filesystem preopen is given DirPerms::all() and FilePerms::READ without FilePerms::WRITE, this wasmtime-wasi enforced access control mechanism can be bypassed by using the wasip2 descriptor.open-at or wasip1 pathopen interfaces by opening a file with OpenFlags::TRUNCATE oflag only, for example: The root cause is that the clause that considered OpenFlags::TRUNCATE did not set openmode |= OpenMode::WRITE;, used later in that function for the access control check against FilePerms for whether opening that file is permitted. With the bug corrected, these calls to open-at and pathopen fail with error-code.not-permitted and ERRNOPERM respectively. The bug in crates/wasi/src/filesystem.rs, Dir::openat, lines 967–969: and the single line fix is: Only wasmtime-wasi embeddings that use a combination of DirPerms::MUTATE with FilePerms::READ are affected by this bug, e.g. those that use in the WasiCtxBuilder: In particular, the Wasmtime project's wasmtime-cli's…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 1 · created ·

    Published from ghsa record GHSA-2r75-cxrj-cmph

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-47261

Advisory: wasmtime-wasi: WASI path_open(TRUNCATE) bypasses `FilePerms::WRITE` host restriction
IDs: CVE-2026-47261, GHSA-2r75-cxrj-cmph
Record: https://patchnext.com/advisories/cve-2026-47261 (revision 1, source checked 26 Oct 2026, 15:43 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: wasmtime-wasi 44.0.2, 36.0.10, 24.0.9. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io wasmtime-wasi: affected >= 37.0.0, < 44.0.2; >= 25.0.0, < 36.0.10; < 24.0.9; fixed in 44.0.2, 36.0.10, 24.0.9

## Suggested inspection (read-only)
- crates.io wasmtime-wasi: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on wasmtime-wasi.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-2r75-cxrj-cmph (GitHub-reviewed advisory GHSA-2r75-cxrj-cmph lists affected ranges: crates.io wasmtime-wasi >=37.0.0 =25.0.0 =0 <24.0.9)

Commands are suggestions: review each one before running it.

Loading voting…