CVE-2026-12327 is a vulnerability in Mozilla Firefox
Published on June 16, 2026
Memory safety bugs fixed in Firefox ESR 140.12, Thunderbird ESR 140.12, Firefox 152 and Thunderbird 152
Memory safety bugs present in Firefox ESR 140.11, Thunderbird ESR 140.11, Firefox 151 and Thunderbird 151. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 152 and Firefox ESR 140.12.
Products Associated with CVE-2026-12327
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Affected Versions
Mozilla Firefox:- Version 140.12, <= 140.* is unaffected.
- Version 152, <= * is unaffected.