CVE-2026-34988 bytecodealliance CVE debrief

Who should care

Defenders managing Wasmtime deployments, especially those using affected versions, should verify exposure and assess the need for updates or compensating controls. The vulnerability is related to data leakage between pooling allocator instances in Wasmtime. Affected versions are prior to 36.0.7, 42.0.2, or 43.0.1. Defenders should prioritize verifying exposure in Wasmtime deployments, especially those using affected versions, and assess the need for vendor

Why it matters

CVE-2026-34988 is a data leakage vulnerability in Wasmtime that requires verification of exposure and assessment of update needs.

• Verify exposure in current Wasmtime deployments
• Assess need for updates to patched versions
• Monitor for potential data leakage
• Evaluate compensating controls if updates are not feasible

Technical summary

The vulnerability is related to data leakage between pooling allocator instances in Wasmtime. Affected versions are prior to 36.0.7, 42.0.2, or 43.0.1. Patches are available for these versions. The vulnerability was published on 2026-04-09 and last modified on 2026-10-12. The CVE record and NVD entry provide details on the vulnerability, but its scope and impact require further verification. Defenders managing Wasmtime deployments should verify exposure and assess the need for updates or compensating controls. The vulnerability is described in the RustSec database and a Wasmtime security advisory on GitHub.

Defensive priority

Defenders should prioritize verifying exposure in Wasmtime deployments, especially those using affected versions, and assess the need for updates or compensating controls.

Recommended defensive actions

• Verify Wasmtime version and check for updates to 36.0.7, 42.0.2, or 43.0.1
• Assess exposure in current deployments
• Monitor for potential data leakage
• Evaluate compensating controls if updates are not feasible
• Review 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 vulnerability is described in the RustSec database and a Wasmtime security advisory on GitHub. Affected versions and patches are mentioned, but specific impacts and exploits are not confirmed. The vulnerability was published on 2026-04-09 and last modified on 2026-10-12. The CVE record and NVD entry provide details on the vulnerability.

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.