CVE-2025-8037 Nameless cookies shadow secure cookies

What is CVE-2025-8037?

CVE-2025-8037 is a critical vulnerability in Mozilla Firefox, published on 22 Jul 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Setting a nameless cookie with an equals sign in the value shadowed other cookies. Even if the nameless cookie was set over HTTP and the shadowed cookie included the `Secure` attribute. This vulnerability was fixed in Firefox 141, Firefox ESR 140.1, Thunderbird 141, and Thunderbird 140.1.

Weakness: CWE-614

Which versions are affected by CVE-2025-8037?

It affects 2 products.

Products include Mozilla Firefox, Mozilla Thunderbird.

How do I fix CVE-2025-8037?

Upgrade to a fixed version.

Is CVE-2025-8037 being exploited?

There is no known exploitation of CVE-2025-8037 in the wild and no public exploit code.

Other vulnerabilities in Mozilla Firefox

• CVE-2019-11708 Mozilla Firefox and Thunderbird Sandbox Escape Exploited Critical 10.0
• CVE-2010-3765 Mozilla Multiple Products Remote Code Execution Exploited Critical 9.8
• CVE-2022-26486 Mozilla Firefox Use-After-Free Exploited Critical 9.6
• CVE-2022-26485 Mozilla Firefox Use-After-Free Exploited High 8.8
• CVE-2019-11707 Mozilla Firefox and Thunderbird Type Confusion Exploited High 8.8

All Mozilla Firefox vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-fw75-5frq-vxhg, UBUNTU-CVE-2025-8037.