CVE-2025-4087

A vulnerability was identified in Thunderbird where XPath parsing could trigger undefined behavior due to missing null checks during attribute access. This could lead to out-of-bounds read access and potentially, memory corruption. This vulnerability was fixed in Firefox 138, Firefox ESR 128.10, Thunderbird 138, and Thunderbird 128.10.

CVSS 3.1

4.8CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

EPSS

0.3% chance of exploitation in the next 30 days; higher than 24% of CVEs (scores of 2026-10-25)

CWE

CWE-125

Published

2025-04-29

Modified

2026-10-05

Record from

the NVD, synced 2026-10-19

Affected

• mozilla:firefox
• mozilla:thunderbird

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1952465
• https://www.mozilla.org/security/advisories/mfsa2025-28/
• https://www.mozilla.org/security/advisories/mfsa2025-29/
• https://www.mozilla.org/security/advisories/mfsa2025-31/
• https://www.mozilla.org/security/advisories/mfsa2025-32/

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