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Description

Memory safety bugs present in Firefox 139 and Thunderbird 139. 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 140 and Thunderbird 140.

PUBLISHED Reserved 2025-06-20 | Published 2025-06-24 | Updated 2026-04-13 | Assigner mozilla

Product status

140 (rpm)
unaffected

140 (rpm)
unaffected

Credits

Andrew McCreight, Gabriele Svelto, Beth Rennie (she/her), Steven Michaud, the Mozilla Fuzzing Team

References

bugzilla.mozilla.org/...966187%2C1966505%2C1970764%2C1942930 (Memory safety bugs fixed in Firefox 140 and Thunderbird 140)

www.mozilla.org/security/advisories/mfsa2025-51/

www.mozilla.org/security/advisories/mfsa2025-54/

cve.org (CVE-2025-6436)

nvd.nist.gov (CVE-2025-6436)

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