CVE-2026-84145 PUBLISHED

Internally found bugs present in Firefox 154, Firefox ESR 153.1, Firefox ESR 140.14 and Firefox ESR 115.39. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, and Firefox ESR 153.2.

• Leo Tenenbaum, Tom Ritter and the Mozilla Fuzzing Team

• High Severity internally found bugs fixed in Firefox 155, Firefox ESR 153.2, Firefox ESR 140.15 and Firefox ESR 115.40
• Low Severity internally found bugs fixed in Firefox 155, Firefox ESR 153.2, Firefox ESR 140.15 and Firefox ESR 115.40
• Moderate Severity internally found bugs fixed in Firefox 155, Firefox ESR 153.2, Firefox ESR 140.15 and Firefox ESR 115.40
• https://www.mozilla.org/security/advisories/mfsa2026-82/
• https://www.mozilla.org/security/advisories/mfsa2026-83/
• https://www.mozilla.org/security/advisories/mfsa2026-84/
• https://www.mozilla.org/security/advisories/mfsa2026-85/