CVE-2025-4087: firefox Out-of-bounds Read — Fix

Description

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.

Is your site exposed to CVE-2025-4087?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

4.8

MEDIUM

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

Weakness Type (CWE)

CWE-125 Out-of-bounds Read

Affected Products

Vendor	Product	Versions
mozilla	firefox	< 128.10
mozilla	firefox	< 138.0
mozilla	thunderbird	< 128.10.0
mozilla	thunderbird	< 138.0

References

Advisories & Patches

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/

Other References

https://bugzilla.mozilla.org/show_bug.cgi?id=1952465 https://lists.debian.org/debian-lts-announce/2025/05/msg00024.html

Frequently Asked Questions

What is 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. It has a CVSS v3.1 base score of 4.8 (MEDIUM).

How severe is CVE-2025-4087? +

CVE-2025-4087 has a CVSS v3.1 score of 4.8 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-4087? +

CVE-2025-4087 affects products from mozilla, specifically: firefox, thunderbird. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-4087? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-50735

pglogical's apply worker does not sufficiently validate the length of certain fields in incoming replication protocol messages before copying them, …

CVE-2026-29013

libcoap contains out-of-bounds read vulnerabilities in OSCORE Appendix B.2 CBOR unwrap handling where get_byte_inc() in src/oscore/oscore_cbor.c relies solely on assert() …

CVE-2026-53566

Out-of-bounds read vulnerability in Citrix Citrix Secure Access Client for Windows. This issue affects Citrix Secure Access Client for Windows: …

CVE-2026-62959

Coturn is a free open source implementation of TURN and STUN Server. From 4.5.2 through 4.14.0, when Coturn is started …

CVE-2026-3508

An Out-of-bounds Read vulnerability in the IOCTL handler in ASUS System Control Interface allows a local user to cause system …

CVE-2025-48520

An improper input validation vulnerability within the AMD Platform Management Framework (PMF) driver can allow a local attacker to read …

CVE-2025-4087