PT-2026-42815 · Bytecode Alliance · Wasmtime-Wasi

Shumbo · CVE-2026-47261 · Published 2026-05-21 · Updated 2026-06-17

Positive Technologies (AI Summary)

CVSS v3.1

7.5

High

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Name of the Vulnerable Software and Affected Versions wasmtime-wasi (affected versions not specified)

Description An access control mechanism bypass exists when a filesystem preopen is configured with DirPerms::all() and FilePerms::READ without FilePerms::WRITE. This allows bypassing restrictions by using the wasip2 descriptor.open-at or wasip1 path open interfaces to open a file using only the OpenFlags::TRUNCATE flag. The issue stems from the Dir::open at() function in crates/wasi/src/filesystem.rs, where the logic handling OpenFlags::TRUNCATE fails to set the open mode to OpenMode::WRITE, which is required for the subsequent access control check against FilePerms.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.

Exploit

Improper Access Control

Weakness Enumeration

CWE-284

Related Identifiers

CVE-2026-47261

GHSA-2R75-CXRJ-CMPH

RUSTSEC-2026-0149

Affected Products

Wasmtime-Wasi

References · 20

• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/47xxx/CVE-2026-47261.json · Exploit
• https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-2r75-cxrj-cmph · Vendor Advisory
• https://osv.dev/vulnerability/GHSA-2r75-cxrj-cmph · Vendor Advisory
• https://osv.dev/vulnerability/RUSTSEC-2026-0149 · Vendor Advisory
• https://osv.dev/vulnerability/DEBIAN-CVE-2026-47261 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-47261 · Security Note
• https://cve.org/CVERecord?id=CVE-2026-47261 · Security Note
• https://osv.dev/vulnerability/UBUNTU-CVE-2026-47261 · Vendor Advisory
• https://ubuntu.com/security/CVE-2026-47261 · Vendor Advisory
• https://security-tracker.debian.org/tracker/CVE-2026-47261 · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2026-47261 · Vendor Advisory
• https://github.com/bytecodealliance/wasmtime/releases/tag/v24.0.9 · Note
• https://github.com/bytecodealliance/wasmtime · Note
• https://github.com/bytecodealliance/wasmtime/releases/tag/v36.0.10 · Note
• https://github.com/bytecodealliance/wasmtime/releases/tag/v45.0.0 · Note