CVE-2025-8037

CRITICAL 9.1CVE-2025-8037 · Published 22/07/2025 · updated 05/10/2026

Package	Affected versions	Patched versions
firefox mozilla	`< 140.1< 141.0`	`140.1141.0`
thunderbird mozilla	`< 140.1< 141.0`	`140.1141.0`

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.

References

bugzilla.mozilla.org/show_bug.cgi · Permissions Required
mozilla.org/security/advisories/mfsa2025-56 · Vendor Advisory
mozilla.org/security/advisories/mfsa2025-59 · Vendor Advisory
mozilla.org/security/advisories/mfsa2025-61 · Vendor Advisory
mozilla.org/security/advisories/mfsa2025-63 · Vendor Advisory

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