CVE-2026-34945
Description
Wasmtime is a runtime for WebAssembly. From 25.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime's Winch compiler contains a bug where a 64-bit table, part of the memory64 proposal of WebAssembly, incorrectly translated the table.size instruction. This bug could lead to disclosing data on the host's stack to WebAssembly guests. The host's stack can possibly contain sensitive data related to other host-originating operations which is not intended to be disclosed to guests. This bug specifically arose from a mistake where the return value of table.size was statically typed as a 32-bit integer, as opposed to consulting the table's index type to see how large the returned register could be. When combined with details about Wnich's ABI, such as multi-value returns, this can be combined to read stack data from the host, within a guest. This vulnerability is fixed in 36.0.7, 42.0.2, and 43.0.1.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
| OS | Version | Status | Fixed in |
|---|---|---|---|
| sles | affected | | |
| debian | forky | fixed | 36.0.7+dfsg-1 |
| debian | sid | fixed | 36.0.7+dfsg-1 |
| debian | trixie | affected | |
References
- https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-m9w2-8782-2946
- https://www.suse.com/security/cve/CVE-2026-34945.html
- https://nvd.nist.gov/vuln/detail/CVE-2026-34945
- https://github.com/bytecodealliance/wasmtime
- https://rustsec.org/advisories/RUSTSEC-2026-0086.html
- https://crates.io/crates/wasmtime
- https://security-tracker.debian.org/tracker/CVE-2026-34945
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.