Mozilla Firefox up to 137.x XPath Parser out-of-bounds

Summaryinfo

A vulnerability was found in Mozilla Firefox up to 137.x. It has been classified as critical. Affected by this issue is some unknown functionality of the component XPath Parser. Performing a manipulation results in out-of-bounds. This vulnerability is cataloged as CVE-2025-4087. It is possible to initiate the attack remotely. There is no exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as critical has been found in Mozilla Firefox up to 137.x. This affects an unknown code block of the component XPath Parser. The manipulation with an unknown input leads to a out-of-bounds vulnerability. CWE is classifying the issue as CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

A vulnerability was identified in Firefox 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 affects Firefox < 138, Firefox ESR < 128.10, Thunderbird < 138, and Thunderbird ESR < 128.10.

The advisory is shared at bugzilla.mozilla.org. This vulnerability is uniquely identified as CVE-2025-4087 since 04/29/2025. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. It demands that the victim is doing some kind of user interaction. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/16/2025).

The vulnerability scanner Nessus provides a plugin with the ID 235040 (Debian dsa-5910 : firefox-esr - security update), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 138 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (235040) and CERT Bund (WID-SEC-2025-1850). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Affected

• Xerox FreeFlow Print Server

Productinfo

Type

• Web Browser

Vendor

• Mozilla

Name

• Firefox

Version

• 137

License

• open-source

Website

• Vendor: https://www.mozilla.org/
• Product: https://www.mozilla.org/en-US/firefox/

CPE 2.3info

• 🔍

CPE 2.2info

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Entryinfo

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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