CVE-2026-109719 Mozilla CVE debrief

Who should care

Defenders responsible for managing Firefox deployments should assess exposure and apply patches as necessary. This includes reviewing system inventory for affected Firefox deployments, verifying Firefox version, and applying patches if necessary. Additionally, defenders should monitor for potential exploitation attempts and review compensating controls for exposed systems while remediation is scheduled and verified.

Why it matters

CVE-2026-109719 is a race condition and use-after-free vulnerability in the Graphics: CanvasWebGL component of Firefox. Defenders should prioritize verifying exposure in their Firefox deployments and applying the available patches.

• Verify exposure in Firefox deployments
• Apply patches to prevent potential exploitation
• Monitor for potential exploitation attempts

Technical summary

A race condition and use-after-free vulnerability exists in the Graphics: CanvasWebGL component of Firefox. This vulnerability was fixed in Firefox 158, Firefox ESR 115.43, and Firefox ESR 153.5. The vulnerability affects the Graphics: CanvasWebGL component, which handles web graphics. The vulnerability could allow an attacker to execute arbitrary code or cause a denial-of-service condition. Defenders should prioritize verifying exposure in their Firefox deployments and applying the available patches. The CVE record and source item provide details on the vulnerability, but additional information from the vendor and other sources may be necessary to fully understand the impact.

Defensive priority

Defenders should prioritize verifying exposure in their Firefox deployments and applying the available patches.

Recommended defensive actions

• Verify Firefox version and apply patches if necessary
• Review system inventory for affected Firefox deployments
• Monitor for potential exploitation attempts
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and source item provide details on the vulnerability, but additional information from the vendor and other sources may be necessary to fully understand the impact. Defenders should verify exposure in their Firefox deployments and apply patches as necessary. The vulnerability affects the Graphics: CanvasWebGL component of Firefox, which is a critical component that handles web graphics. The vulnerability was fixed in Firefox 158, Firefox ESR 115.43, and Firefox ESR 153.5. There is no evidence of exploitation in the wild,

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.