Mozilla Firefox up to 115.38/140.13/153/153.0 Networking privileges management

Summaryinfo

A vulnerability categorized as critical has been discovered in Mozilla Firefox up to 115.38/140.13/153/153.0. Affected is an unknown function of the component Networking. Executing a manipulation can lead to privileges management. This vulnerability appears as CVE-2026-74935. The attack may be performed from remote. There is no available exploit. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in Mozilla Firefox up to 115.38/140.13/153/153.0. It has been declared as critical. This vulnerability affects an unknown functionality of the component Networking. The manipulation with an unknown input leads to a privileges management vulnerability. The CWE definition for the vulnerability is 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. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

Privilege escalation in the DOM: Networking component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

The advisory is shared for download at bugzilla.mozilla.org. This vulnerability was named CVE-2026-74935 since 08/17/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $5k-$25k (estimation calculated on 08/24/2026). The MITRE ATT&CK project declares the attack technique as T1068.

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 115.39, 140.14, 153.1 or 154 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (339042). Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

• Web Browser

Vendor

• Mozilla

Name

• Firefox

Version

• 115.0
• 115.1
• 115.2
• 115.3
• 115.4
• 115.5
• 115.6
• 115.7
• 115.8
• 115.9
• 115.10
• 115.11
• 115.12
• 115.13
• 115.14
• 115.15
• 115.16
• 115.17
• 115.18
• 115.19
• 115.20
• 115.21
• 115.22
• 115.23
• 115.24
• 115.25
• 115.26
• 115.27
• 115.28
• 115.29
• 115.30
• 115.31
• 115.32
• 115.33
• 115.34
• 115.35
• 115.36
• 115.37
• 115.38
• 140.0
• 140.1
• 140.2
• 140.3
• 140.4
• 140.5
• 140.6
• 140.7
• 140.8
• 140.9
• 140.10
• 140.11
• 140.12
• 140.13
• 153

License

• open-source

Website

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

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Once again VulDB remains the best source for vulnerability data.

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