Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
Wasmtime versions 37.0.0 and 37.0.1 leak host memory in the C/C++ API when `anyref` or `externref` values are used; the Rust crate and versions 36.x and earlier are not affected. The package wasmtime-c-api-impl (crates.io, versions 37.0.0 to before 37.0.2) and wasmtime-bin (PyPI, versions before 37.0.2) are listed as affected. Upgrade to 37.0.2, which fixes the leak. If upgrading is not possible, the only workaround is to avoid `externref` and `anyref` in the C/C++ API.
Not analysed yet
We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.
Severity and exploitation
| Score | Rating | CVSS | Vector | Source |
|---|---|---|---|---|
| 1.0 | Low | 4.0 | CVSS:4.0/AV:A/AC:L/AT:P/PR:L/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L | CNA (GitHub_M) |
- CISA KEV Not listed.
- EPSS 0.0019, the 9th percentile, on 15 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 14:43 UTC First seen by agentprime
- 31 Oct 2026, 14:43 UTC Confirmed by OSV
Sources
- GitHub Advisory Database: GHSA-vvp9-h8p2-xwfc
- OSV: GHSA-vvp9-h8p2-xwfc
- github.com/bytecodealliance/wasmtime/security/advisories/GHSA-vvp9-h8p2-xwfc
- nvd.nist.gov/vuln/detail/CVE-2025-61670
- github.com/bytecodealliance/wasmtime/commit/adff9d9d0f09569203709d5687e5a7dc8e1ad0a3
- github.com/bytecodealliance/wasmtime
- github.com/bytecodealliance/wasmtime/releases/tag/v37.0.2
- github.com/pypa/advisory-database/tree/main/vulns/wasmtime-bin/PYSEC-2025-268.yaml