CVE-2026-34946 bytecodealliance CVE debrief

Who should care

Defenders responsible for Wasmtime installations should assess their exposure and prioritize updating to the patched versions to prevent potential host panics. This includes operators, platform administrators, vulnerability management teams, and security teams who need to be aware of the potential impact of this vulnerability on their systems.

Why it matters

Defenders should care about CVE-2026-34946 because it can cause host panics in Wasmtime, and updating to patched versions is necessary to prevent this issue.

• Potential host panics due to the execution of `table.fill` by the Winch compiler.
• Need to verify and update Wasmtime installations to patched versions.

Technical summary

The vulnerability occurs when the Winch compiler in Wasmtime executes `table.fill`, causing a host panic. This issue has been addressed in specific versions of Wasmtime (36.0.7, 42.0.2, and 43.0.1). The vulnerability is related to the Winch compiler's execution of `table.fill`, which can cause a host panic. Defenders should prioritize reviewing and updating Wasmtime to the patched versions to prevent potential host panics. The evidence provided includes details from the RustSec database and the Wasmtime security advisory on GitHub.

Defensive priority

Defenders should prioritize reviewing and updating Wasmtime to the patched versions to prevent potential host panics.

Recommended defensive actions

• Review and update Wasmtime to the patched versions (36.0.7, 42.0.2, or 43.0.1) to prevent potential host panics.
• Monitor for any potential exploitation attempts or anomalies in Wasmtime usage.
• Verify the integrity of Wasmtime installations and ensure that they are up-to-date with the latest security patches.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.

Evidence notes

The evidence provided includes details from the RustSec database and the Wasmtime security advisory on GitHub. The vulnerability is related to the Winch compiler's execution of `table.fill`, which can cause a host panic.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.