CVE-2026-58494 Wasmtime: WASI hard links bypass wasmtime-wasi's FilePerms for destination
A WASI guest can overwrite host files via hard links or renames, bypassing read-only file permissions in the Wasmtime runtime.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-58494?
CVE-2026-58494 is a medium-severity missing authorization vulnerability in bytecodealliance wasmtime, published on 8 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
Wasmtime is a runtime for WebAssembly. Prior to 24.0.11, 36.0.12, 45.0.3, and 46.0.1, wasmtime-wasi hard-link creation and renaming check directory permissions but not matching FilePerms on source and destination preopens, allowing a WASI guest with a read-only source file capability to overwrite host files exposed as FilePerms::READ through wasip1, wasip2, or wasip3 filesystem interfaces. This issue is fixed in versions 24.0.11, 36.0.12, 45.0.3, and 46.0.1.
Which versions are affected by CVE-2026-58494?
9 open source packages ship an affected version, including wasmtime-wasi.
| Package | Affected | Fixed in |
|---|---|---|
wasmtime-wasi crates.io | All versions | 24.0.11 |
wasmtime-wasi crates.io | All versions | 24.0.11 |
wasmtime-wasi crates.io | From 0.0.0-0 | 24.0.11, 36.0.12, 45.0.3, 46.0.1 |
wasmtime-wasi crates.io | From 25.0.0 | 36.0.12 |
wasmtime-wasi crates.io | From 25.0.0 | 36.0.12 |
wasmtime-wasi crates.io | From 37.0.0 | 45.0.3 |
3 more packages
wasmtime-wasi crates.io | From 37.0.0 | 45.0.3 |
wasmtime-wasi crates.io | From 46.0.0 | 46.0.1 |
wasmtime-wasi crates.io | From 46.0.0 | 46.0.1 |
How do I fix CVE-2026-58494?
Upgrade wasmtime-wasi to a fixed version for your release line: 24.0.11, 36.0.12, 45.0.3 or 46.0.1.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-58494 being exploited?
There is no known exploitation of CVE-2026-58494 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-58494, GHSA-4ch3-9j33-3pmj, JLSEC-2026-1368, MINI-hm6w-m864-527m, MINI-pw4r-vcq9-pjp4, MINI-v58j-vw6j-p685 and 2 more.