Mozilla Firefox up to 149 NSS memory corruption

Summaryinfo

A vulnerability labeled as critical has been found in Mozilla Firefox up to 149. This impacts an unknown function of the component NSS. Such manipulation leads to memory corruption. This vulnerability is documented as CVE-2026-6766. The attack can be executed remotely. There is not any exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Mozilla Firefox up to 149 and classified as critical. Affected by this issue is an unknown part of the component NSS. 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. CVE summarizes:

Incorrect boundary conditions in the Libraries component in NSS. This vulnerability was fixed in Firefox 150 and Firefox ESR 140.10.

The advisory is available at bugzilla.mozilla.org. This vulnerability is handled as CVE-2026-6766 since 04/21/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Successful exploitation requires user interaction by the victim. The technical details are unknown and an exploit is not available. The structure of the vulnerability defines a possible price range of USD $5k-$25k at the moment (estimation calculated on 05/20/2026).

The vulnerability scanner Nessus provides a plugin with the ID 309071 (Linux Distros Unpatched Vulnerability : CVE-2026-6766), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 150 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (309071) and CERT Bund (WID-SEC-2026-1228). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Affected

• Debian Linux
• Red Hat Enterprise Linux
• SUSE Linux
• Oracle Linux
• SUSE openSUSE
• RESF Rocky Linux
• Mozilla Thunderbird
• Mozilla Firefox ESR
• Mozilla Firefox

Productinfo

Type

• Web Browser

Vendor

• Mozilla

Name

• Firefox

Version

• 149

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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Entryinfo

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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