Wasmtime has host panic with `fd_renumber` WASIp1 function
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- None · None · Low
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub.
Summary
Wasmtime is a runtime for WebAssembly. Prior to versions 24.0.4, 33.0.2, and 34.0.2, a bug in Wasmtime's implementation of the WASIp1 set of import functions can lead to a WebAssembly guest inducing a panic in the host (embedder). The specific bug is triggered by calling `path_open` after calling `fd_renumber` with either two equal argument values or a second argument being equal to a previously-closed file descriptor number value. The corrupt state introduced in `fd_renumber` will lead to the subsequent opening of a file descriptor to panic. This panic cannot introduce memory unsafety or allow WebAssembly to break outside of its sandbox, however. There is no possible heap corruption or memory unsafety from this panic. This bug is in the implementation of Wasmtime's `wasmtime-wasi` crate which provides an implementation of WASIp1. The bug requires a specially crafted call to `fd_renumber` in addition to the ability to open a subsequent file descriptor. Opening a second file descriptor is only possible when a preopened directory was provided to the guest, and this is common amongst embeddings. A panic in the host is considered a denial-of-service vector for WebAssembly embedders and is thus a security issue in Wasmtime. This bug does not affect WASIp2 and embedders using components. In accordance with Wasmtime's release process, patch releases are available as 24.0.4, 33.0.2, and 34.0.2. Users of other release of Wasmtime are recommended to move to a supported release of Wasmtime. Embedders who are using components or are not providing guest access to create more file descriptors (e.g. via a preopened filesystem directory) are not affected by this issue. Otherwise, there is no workaround at this time, and affected embeddings are recommended to update to a patched version which will not cause a panic in the host.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| bytecodealliance | wasmtime | before 24.0.4; 33.0.0 to before 33.0.2; 34.0.0 to before 34.0.2 | 24.0.4, 33.0.2, 34.0.2 | Patch available | CNA |
| — | wasmtime-wasi (crates.io) | before 24.0.4 | 24.0.4 | Patch available | GHSA-fm79-3f68-h2fc |
| — | wasmtime-wasi (crates.io) | 25.0.0 to before 33.0.2 | 33.0.2 | Patch available | GHSA-fm79-3f68-h2fc |
| — | wasmtime-wasi (crates.io) | 34.0.0 to before 34.0.2 | 34.0.2 | Patch available | GHSA-fm79-3f68-h2fc |
| — | wasmtime (crates.io) | 10.0.0 to before 24.0.4 | 24.0.4 | Patch available | GHSA-fm79-3f68-h2fc |
| — | wasmtime (crates.io) | 33.0.0 to before 33.0.2 | 33.0.2 | Patch available | GHSA-fm79-3f68-h2fc |
| — | wasmtime (crates.io) | 34.0.0 to before 34.0.2 | 34.0.2 | Patch available | GHSA-fm79-3f68-h2fc |
- wasmtime Vendorbytecodealliance Affected before 24.0.4; 33.0.0 to before 33.0.2; 34.0.0 to before 34.0.2 Fixed in 24.0.4, 33.0.2, 34.0.2 Patch available CNA
- wasmtime-wasi (crates.io) Vendor— Affected before 24.0.4 Fixed in 24.0.4 Patch available GHSA-fm79-3f68-h2fc
- wasmtime-wasi (crates.io) Vendor— Affected 25.0.0 to before 33.0.2 Fixed in 33.0.2 Patch available GHSA-fm79-3f68-h2fc
- wasmtime-wasi (crates.io) Vendor— Affected 34.0.0 to before 34.0.2 Fixed in 34.0.2 Patch available GHSA-fm79-3f68-h2fc
- wasmtime (crates.io) Vendor— Affected 10.0.0 to before 24.0.4 Fixed in 24.0.4 Patch available GHSA-fm79-3f68-h2fc
- wasmtime (crates.io) Vendor— Affected 33.0.0 to before 33.0.2 Fixed in 33.0.2 Patch available GHSA-fm79-3f68-h2fc
- wasmtime (crates.io) Vendor— Affected 34.0.0 to before 34.0.2 Fixed in 34.0.2 Patch available GHSA-fm79-3f68-h2fc
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:bytecodealliance:wasmtime:*:*:*:*:*:rust:*:* | before 24.0.4; 33.0.0 to before 33.0.2; 34.0.0 to before 34.0.2 | Vulnerable | bytecodealliance |
- cpe:2.3:a:bytecodealliance:wasmtime:*:*:*:*:*:rust:*:* Versions before 24.0.4; 33.0.0 to before 33.0.2; 34.0.0 to before 34.0.2 Vulnerable ·bytecodealliance
Remediation
- Fix · CNA wasmtime (bytecodealliance) Fixed in 24.0.4, 33.0.2, 34.0.2
- Fix · GHSA-fm79-3f68-h2fc wasmtime-wasi (crates.io) Fixed in 24.0.4 Advisory →
- Fix · GHSA-fm79-3f68-h2fc wasmtime-wasi (crates.io) Fixed in 33.0.2 Advisory →
- Fix · GHSA-fm79-3f68-h2fc wasmtime-wasi (crates.io) Fixed in 34.0.2 Advisory →
- Fix · GHSA-fm79-3f68-h2fc wasmtime (crates.io) Fixed in 24.0.4 Advisory →
- Fix · GHSA-fm79-3f68-h2fc wasmtime (crates.io) Fixed in 33.0.2 Advisory →
- Fix · GHSA-fm79-3f68-h2fc wasmtime (crates.io) Fixed in 34.0.2 Advisory →
Vendor assessments
Timeline
- 2026-10-02 Threatist record created from CVE-2025-53901
- 2026-10-03 Alias added: GHSA-fm79-3f68-h2fc
References
Advisory 2
Other 10
- https://docs.wasmtime.dev/security-what-is-considered-a-security-vulnerability.html
- https://docs.wasmtime.dev/stability-release.html
- https://github.com/WebAssembly/WASI/blob/e1aa1cae4dda4c1f70f23fe11e922aae92f240a8/legacy/preview1/witx/wasi_snapshot_preview1.witx#L245-L260
- https://github.com/bytecodealliance/wasmtime/blob/037a6edadbc225decbea00a551aabf04203717d9/crates/wasi/src/preview1.rs#L1824-L1836
- https://github.com/bytecodealliance/wasmtime/pull/11277
- https://github.com/bytecodealliance/wasmtime/pull/11278
- https://github.com/bytecodealliance/wasmtime/pull/11279
- https://github.com/bytecodealliance/wasmtime/pull/11281
- https://github.com/bytecodealliance/wasmtime
- https://rustsec.org/advisories/RUSTSEC-2025-0046.html
More bytecodealliance Wasmtime vulnerabilities
- TI-2026-21632 Wasmtime is vulnerable to panic when dropping a `[Typed]Func::call_async` future CVSS 4.0MEDIUM 6.9
- TI-2023-11636 Guest-controlled out-of-bounds read/write on x86_64 in wasmtime CVSS 3.1CRITICAL 10.0
- TI-2022-18765 Wasmtime vulnerable to data leakage between instances in the pooling allocator CVSS 3.1HIGH 8.6
- TI-2022-08604 Use after free in Wasmtime CVSS 3.1CRITICAL 9.8
- TI-2022-18766 wasmtime_trap_code C API function has out of bounds write vulnerability CVSS 3.1CRITICAL 9.8
- TI-2026-27209 Wasmtime with Winch compiler backend on aarch64 may allow a sandbox-escaping memory access CVSS 4.0CRITICAL 9.0
Sources
- CVE-2025-53901 · CVE Program
- CVE-2025-53901 · NVD
- FIRST EPSS
- GHSA-fm79-3f68-h2fc · GitHub Advisory Database · CC BY 4.0
- CVE-2025-53901 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences