Mozilla Firefox prior 140.14/153.1/154 Safe Browsing privileges management

Summaryinfo

A vulnerability marked as critical has been reported in Mozilla Firefox. Impacted is an unknown function of the component Safe Browsing. Performing a manipulation results in privileges management. This vulnerability is known as CVE-2026-74957. Remote exploitation of the attack is possible. No exploit is available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Mozilla Firefox. It has been classified as critical. This affects an unknown code of the component Safe Browsing. The manipulation with an unknown input leads to a privileges management vulnerability. CWE is classifying the issue as CWE-269. The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

Mitigation bypass in the Safe Browsing component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

The advisory is shared at bugzilla.mozilla.org. This vulnerability is uniquely identified as CVE-2026-74957 since 08/17/2026. 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 $5k-$25k at the moment (estimation calculated on 08/24/2026). MITRE ATT&CK project uses the attack technique T1068 for this issue.

The vulnerability scanner Nessus provides a plugin with the ID 339042 (Debian dsa-6461 : thunderbird - security update), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 140.14, 153.1 or 154 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (339042). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

• Web Browser

Vendor

• Mozilla

Name

• Firefox

License

• open-source

Website

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

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

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