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8.1 High

CVE-2026-12327 Memory safety bugs present in Firefox ESR 140.11, Thunderbird ESR 140.11, Firefox 151 and Thunderbird 151

Description

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, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12.

Affected products and versions

Product Affected versions Fixed in
Firefox 152 earliest → < 152 152
Firefox 140.12 earliest → < 140.12 140.12
Thunderbird 152 earliest → < 152 152
Thunderbird 140.12 earliest → < 140.12 140.12

Other CVEs of Firefox

The 2221 CVEs of Firefox →
CVE-2026-120572 Incorrect boundary conditions in the Layout: Block and Inline component 8.8 High CVE-2026-118027 Frame poisoning in the Layout component 9.1 Critical CVE-2026-118025 Other issue in the SVG component 8.8 High CVE-2026-118024 Use-after-free in the Graphics: Text component 8.8 High
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