Mozilla Firefox up to 137.x memory corruption

Summaryinfo

A vulnerability marked as critical has been reported in Mozilla Firefox up to 137.x. Affected by this issue is some unknown functionality. The manipulation leads to memory corruption. This vulnerability is uniquely identified as CVE-2025-4091. The attack is possible to be carried out remotely. No exploit exists. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Mozilla Firefox up to 137.x and classified as critical. This issue affects an unknown code. The manipulation with an unknown input leads to a memory corruption vulnerability. Using CWE to declare the problem leads to CWE-119. The product performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

Memory safety bugs present in Firefox 137, Thunderbird 137, Firefox ESR 128.9, and Thunderbird 128.9. 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 affects Firefox < 138, Firefox ESR < 128.10, Thunderbird < 138, and Thunderbird ESR < 128.10.

It is possible to read the advisory at bugzilla.mozilla.org. The identification of this vulnerability is CVE-2025-4091 since 04/29/2025. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. It demands that the victim is doing some kind of user interaction. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 08/16/2025).

The vulnerability scanner Nessus provides a plugin with the ID 234929 (Mozilla Firefox ESR < 128.10), 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 (234929) and CERT Bund (WID-SEC-2025-1850). Be aware that VulDB is the high quality source for vulnerability data.

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

Be aware that VulDB is the high quality source for vulnerability data.

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