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critical9.8

CVE-2026-5734

Memory safety bugs present in Firefox ESR 140.9.0, Thunderbird ESR 140.9.0, Firefox 149.0.1 and Thunderbird 149.0.1.

Impact

Memory safety bugs present in Firefox ESR 140.9.0, Thunderbird ESR 140.9.0, Firefox 149.0.1 and Thunderbird 149.0.1. 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 149.0.2, Firefox ESR 140.9.1, Thunderbird 149.0.2, and Thunderbird 140.9.1.

Affected products

VendorProductAffected versions
MozillaFirefox
before 140.9.1
before 149.0.2
MozillaThunderbird
before 140.9.1
before 149.0.2

Weakness classification

CWE-787CWE-120

References