CVE-2026-34943
Description
Wasmtime is a runtime for WebAssembly. Prior to 24.0.7, 36.0.7, 42.0.2, and 43.0.1, Wasmtime contains a possible panic which can happen when a flags-typed component model value is lifted with the Val type. If bits are set outside of the set of flags the component model specifies that these bits should be ignored but Wasmtime will panic when this value is lifted. This panic only affects wasmtime's implementation of lifting into Val, not when using the flags! macro. This additionally only affects flags-typed values which are part of a WIT interface. This has the risk of being a guest-controlled panic within the host which Wasmtime considers a DoS vector. This vulnerability is fixed in 24.0.7, 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-m758-wjhj-p3jq
- https://www.suse.com/security/cve/CVE-2026-34943.html
- https://nvd.nist.gov/vuln/detail/CVE-2026-34943
- https://github.com/bytecodealliance/wasmtime
- https://rustsec.org/advisories/RUSTSEC-2026-0085.html
- https://crates.io/crates/wasmtime
- https://security-tracker.debian.org/tracker/CVE-2026-34943
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.