CVE-2026-92011 Mozilla CVE debrief

Who should care

Defenders responsible for managing Mozilla Firefox, Thunderbird, and ESR products should assess exposure and prioritize patching vulnerable systems, especially those exposed to the internet.

Why it matters

CVE-2026-92011 is a high-severity vulnerability that allows for privilege escalation in Mozilla Firefox, Thunderbird, and ESR products. Defenders should prioritize patching vulnerable systems, especially those exposed to the internet, as this vulnerability could allow attackers to gain elevated privileges.

• Potential privilege escalation
• Elevation of privileges could lead to further exploitation
• Requires verification of affected versions and exposure

Technical summary

The vulnerability is caused by incorrect boundary conditions in the Graphics: CanvasWebGL component, allowing for privilege escalation. It was fixed in Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3. The vulnerability allows attackers to gain elevated privileges, and defenders should prioritize patching vulnerable systems, especially those exposed to the internet. The CVE record and NVD details provide information on the vulnerability, its impact, and affected versions.

Defensive priority

Defenders should prioritize patching vulnerable systems, especially those exposed to the internet, as this vulnerability could allow attackers to gain elevated privileges.

Recommended defensive actions

• Patch vulnerable systems, especially those exposed to the internet
• Verify and apply updates for Firefox, Firefox ESR, and Thunderbird
• Monitor systems for potential exploitation attempts
• Review compensating controls for exposed systems while remediation is scheduled and verified
• 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
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and NVD details provide information on the vulnerability, its impact, and affected versions. Vendor advisories from Mozilla offer additional context and mitigation strategies. The vulnerability was fixed in Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3. However, specific details about the vulnerability and its potential impact are limited, and defenders should verify affected versions and exposure.

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.