Mozilla Firefox up to 143 OBJECT Tag cross site scripting

Summaryinfo

A vulnerability was found in Mozilla Firefox up to 143. It has been rated as problematic. Affected by this vulnerability is an unknown functionality of the component OBJECT Tag Handler. Performing a manipulation results in cross site scripting. This vulnerability is identified as CVE-2025-11712. The attack can be initiated remotely. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as problematic, was found in Mozilla Firefox up to 143. This affects an unknown function of the component OBJECT Tag Handler. The manipulation with an unknown input leads to a cross site scripting vulnerability. CWE is classifying the issue as CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. This is going to have an impact on integrity. The summary by CVE is:

A malicious page could have used the type attribute of an OBJECT tag to override the default browser behavior when encountering a web resource served without a content-type. This could have contributed to an XSS on a site that unsafely serves files without a content-type header. This vulnerability affects Firefox < 144, Firefox ESR < 140.4, Thunderbird < 144, and Thunderbird < 140.4.

It is possible to read the advisory at bugzilla.mozilla.org. This vulnerability is uniquely identified as CVE-2025-11712 since 10/13/2025. 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. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 11/16/2025). The attack technique deployed by this issue is T1059.007 according to MITRE ATT&CK.

The vulnerability scanner Nessus provides a plugin with the ID 270625 (Debian dsa-6025 : firefox-esr - security update), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 144 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (270625) and CERT Bund (WID-SEC-2025-2275). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

• Debian Linux
• Amazon Linux 2
• Red Hat Enterprise Linux
• SUSE Linux
• Oracle Linux
• SUSE openSUSE
• RESF Rocky Linux
• IGEL OS
• Mozilla Firefox
• Mozilla Firefox ESR
• Mozilla Thunderbird

Productinfo

Type

• Web Browser

Vendor

• Mozilla

Name

• Firefox

Version

• 143

License

• open-source

Website

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

CPE 2.3info

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CPE 2.2info

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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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