Vulnerability CriticalRUSTSEC-2026-0095 · wasmtime
RUSTSEC-2026-0095: Wasmtime with Winch compiler backend may allow a sandbox-escaping memory access
Short answerA security vulnerability in the wasmtime crate: Wasmtime with Winch compiler backend may allow a sandbox-escaping memory access. GitHub rates it Critical. Fixed in 36.0.7, 42.0.2, 43.0.1: update to a fixed version.
| Crate | wasmtime |
|---|---|
| Type | Vulnerability |
| Affected versions | Before 36.0.7; from 37.0.0 before 42.0.2; from 43.0.0 before 43.0.1. |
| Fixed in | 36.0.7, 42.0.2, 43.0.1 |
| Severity | Critical (GitHub rating) CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H |
| Published | 2026-04-09 |
| Last changed | 2026-10-12 |
| Also known as | CVE-2026-34987, GHSA-xx5w-cvp6-jv83 |
What to do
- See which version you have:
cargo tree -i wasmtime(it also shows which of your dependencies pulls it in). - Update within your version requirement:
cargo update -p wasmtime. If the fix is a newer major or minor than your requirement allows, raise it in Cargo.toml (for examplewasmtime = "43.0.1") or update the dependency that pulls it in. - Check again with
cargo audit, or paste your Cargo.lock into our Cargo.toml checker.
Details from the advisory
This is an entry in the RustSec database for the Wasmtime security advisory located at https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-xx5w-cvp6-jv83 For more information see the GitHub-hosted security advisory.
References
- Package: crates.io/crates/wasmtime
- Advisory: rustsec.org/advisories/RUSTSEC-2026-0095.html
- Web: github.com/bytecodealliance/wasmtime/pull/13014
From the RustSec Advisory Database (CC0-1.0) via the OSV export, downloaded Oct 24, 2026. Severity score computed from the published CVSS vector.
Other advisories for wasmtime
- Vulnerability MediumRUSTSEC-2021-0110 · 2021-09-17Multiple Vulnerabilities in Wasmtime
- VulnerabilityRUSTSEC-2022-0016 · 2022-03-31Use after free with `externref`s and epoch interruption in Wasmtime
- VulnerabilityRUSTSEC-2022-0075 · 2022-11-10Bug in pooling instance allocator
- Vulnerability HighRUSTSEC-2022-0076 · 2022-11-10Bug in Wasmtime implementation of pooling instance allocator
- VulnerabilityRUSTSEC-2022-0095 · 2022-06-27Miscompilation of `i8x16.swizzle` and `select` with v128 inputs
- VulnerabilityRUSTSEC-2022-0096 · 2022-02-17Invalid drop of VMExternRef from partially-initialized instances in the pooling instance allocator
- Vulnerability LowRUSTSEC-2022-0097 · 2022-11-07Out of bounds write in `wasmtime_trap_code` C API function
- Vulnerability HighRUSTSEC-2022-0098 · 2022-11-05Data leakage between instances in the pooling allocator
Up next
Same cratewasmtime: security historyEvery advisory for this crate, and whether it is safe to use today.Read it next →Did this answer your question?