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CVE-2026-92011: Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-15 · updated 2026-10-06
• Weakness: CWE-120

Description

Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component. This 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.

Affected products

• Mozilla Firefox: before 115.41.0; from 116.0 before 140.16.0; from 141.0 before 153.3.0; from 154.0.0 before 156.0.0 — fixed in 115.41.0, 140.16.0, 153.3.0, 156.0.0
• Mozilla Thunderbird: before 140.16.0; from 141.0 before 153.3.0; from 154.0 before 156.0 — fixed in 140.16.0, 153.3.0, 156.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 115.41.0, 140.16.0, 153.3.0, 156.0.0; Mozilla Thunderbird 140.16.0, 153.3.0, 156.0. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=2058068
• https://www.mozilla.org/security/advisories/mfsa2026-90/
• https://www.mozilla.org/security/advisories/mfsa2026-91/
• https://www.mozilla.org/security/advisories/mfsa2026-92/
• https://www.mozilla.org/security/advisories/mfsa2026-93/
• https://www.mozilla.org/security/advisories/mfsa2026-94/
• https://www.mozilla.org/security/advisories/mfsa2026-95/
• https://www.mozilla.org/security/advisories/mfsa2026-96/

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