CVE-2026-109765 Mozilla CVE debrief

Who should care

Defenders responsible for managing Firefox deployments, especially those using versions prior to 158 or Firefox ESR 153.5, should assess their exposure and prioritize remediation. The vulnerability could potentially allow attackers to execute arbitrary code or cause a denial-of-service condition. Defenders should prioritize verifying exposure in their Firefox deployments, especially for versions prior to 158 or Firefox ESR 153.5, and assess the need for

Why it matters

Defenders should prioritize verifying exposure in their Firefox deployments, especially for versions prior to 158 or Firefox ESR 153.5, and assess the need for immediate remediation due to the race condition, use-after-free vulnerability in the Graphics: Text component.

• Verification of Firefox version and potential exposure
• Assessment of system configurations for vulnerability
• Monitoring for suspicious activity related to the Graphics: Text component
• Remediation prioritization for affected systems

Technical summary

A race condition, use-after-free vulnerability exists in the Graphics: Text component of Firefox. This issue was addressed in Firefox 158 and Firefox ESR 153.5. The vulnerability could potentially allow attackers to execute arbitrary code or cause a denial-of-service condition. The CVE record and associated source item provide details on the vulnerability, including its existence in the Graphics: Text component and the fixed versions. The vulnerability was reported by a researcher and is addressed in Firefox 158 and Firefox ESR 153.5.

Defensive priority

Defenders should prioritize verifying exposure in their Firefox deployments, especially for versions prior to 158 or Firefox ESR 153.5, and assess the need for immediate remediation.

Recommended defensive actions

• Verify Firefox version and update to 158 or Firefox ESR 153.5 if necessary
• Review system configurations for potential exposure
• Monitor for any suspicious activity related to the Graphics: Text component
• Assess the need for immediate remediation due to the race condition, use-after-free vulnerability in the Graphics: Text component
• Prioritize verifying exposure in Firefox deployments, especially for versions prior to 158 or Firefox ESR 153.5
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The CVE record and associated source item provide details on the vulnerability, including its existence in the Graphics: Text component and the fixed versions. The vulnerability was reported by a researcher and is addressed in Firefox 158 and Firefox ESR 153.5. There is no evidence of public exploitation at the time of disclosure. The CVE record and associated source item provide details on the vulnerability, including its existence in the Graphics: Text component and the fixed versions.

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.