CVE-2025-5268

Memory safety bugs present in Firefox 138, Thunderbird 138, Firefox ESR 128.10, and Thunderbird 128.10. 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 139, Firefox ESR 128.11, Thunderbird 139, and Thunderbird 128.11.

CVSS 3.1

8.1CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

0.5% chance of exploitation in the next 30 days; higher than 43% of CVEs (scores of 2026-10-25)

CWE

CWE-119

Published

2025-05-27

Modified

2026-10-05

Record from

the NVD, synced 2026-10-19

Affected

• mozilla:firefox
• mozilla:thunderbird

References

• https://bugzilla.mozilla.org/buglist.cgi?bug_id=1950136%2C1958121%2C1960499%2C1962634
• https://www.mozilla.org/security/advisories/mfsa2025-42/
• https://www.mozilla.org/security/advisories/mfsa2025-44/
• https://www.mozilla.org/security/advisories/mfsa2025-45/
• https://www.mozilla.org/security/advisories/mfsa2025-46/

Check your stackJSON