Firefox <155 memory corruption CVE-2026-84143
CVE-2026-84143 Published on September 1, 2026
Internally found bugs fixed in Firefox 155, Firefox ESR 153.2 and Firefox ESR 140.15
Internally found bugs present in Firefox 154, Firefox ESR 153.1 and Firefox ESR 140.14. 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 140.15, and Firefox ESR 153.2.
Products Associated with CVE-2026-84143
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Affected Versions
Mozilla Firefox:- Version 140.15, <= 140.* is unaffected.
- Version 153.2, <= 153.* is unaffected.
- Version 155, <= * is unaffected.