GHSA-897f-g5gm-fmxm

Source

https://github.com/advisories/GHSA-897f-g5gm-fmxm

Import Source

https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-897f-g5gm-fmxm/GHSA-897f-g5gm-fmxm.json

JSON Data

https://api.osv.dev/v1/vulns/GHSA-897f-g5gm-fmxm

Aliases

CVE-2026-115889
RUSTSEC-2026-0380

Published

2026-10-23T22:02:20Z

Modified

2026-10-23T22:25:51Z

Severity

9.9 (Critical) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H CVSS Calculator

Summary

Wasmtime: Bit-packing in Cranelift compiler causes silent overflow and miscompilation

Details

Summary

In Wasmtime prior to v43, the Cranelift compiler backend bit-packs its SSA value indices in a way that can result in silent overflow in release builds, and result in incorrect value references in the IR resulting in arbitrary miscompilation. A very large Wasm function body, or one that is specially crafted to use many SSA values, can use this to force type-confusion or other arbitrary side-effects and escape the sandbox.

Cranelift was changed in Wasmtime v43 to use a full u32 index, with checks if that limit is exceeded, and so is no longer susceptible to this bug.

Impact

A Wasmtime engine with default settings (using the Cranelift backend) on any architecture/platform could experience a sandbox escape from a specially-crafted Wasm module.

Patches

Wasmtime v36.0.19 has been released which fixes this issue.

Database specific

{
    "cwe_ids":  [
        "CWE-197",
        "CWE-843"
    ],
    "github_reviewed":  true,
    "github_reviewed_at":  "2026-10-23T22:02:20Z",
    "nvd_published_at":  null,
    "severity":  "CRITICAL"
}

References

Affected packages

crates.io / wasmtime

Package

Name: wasmtime; View open source insights on deps.dev
Purl: pkg:cargo/wasmtime

Affected ranges

Type: SEMVER
Events: Introduced

0 Unknown introduced version / All previous versions are affected

Fixed

36.0.19

Database specific

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-897f-g5gm-fmxm/GHSA-897f-g5gm-fmxm.json"

crates.io / wasmtime

Package

Name: wasmtime; View open source insights on deps.dev
Purl: pkg:cargo/wasmtime

Affected ranges

Type: SEMVER
Events: Introduced

37.0.0

Fixed

43.0.0

Database specific

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-897f-g5gm-fmxm/GHSA-897f-g5gm-fmxm.json"