CVE-2026-74963
MediumCVSS 5.4Exploitation Probability (EPSS)
Low risk3th percentile - higher than 3% of all known CVEs
Summary
Vulnerability in the Networking: Cookies component allows bypassing the same-origin policy. It was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
Risk Assessment
Bypassing the same-origin policy in the context of cookies could allow an attacker to steal sessions or manipulate cookies, potentially leading to account takeover.
Recommendation
Update Firefox or Thunderbird to the latest available version that includes the fix.
Other vulnerabilities in Firefox
See all- CVE-2026-120572Unknown
Incorrect boundary conditions in the Layout: Block and Inline component. This vulnerability was fixed in Firefox 159.0.1.
- CVE-2026-113470Medium
Mozilla blocked compromised intermediate eMudhra certificates via OneCRL on October 17, and the list was distributed to clients via RemoteSettings the same day. This update contains the updated OneCRL block list, ensuring clients will block the compromised certificates even if RemoteSettings is disabled by policy or otherwise unavailable in the user's network environment. The vulnerability was fixed in Firefox 158.0.1, Firefox ESR 153.5.1, Firefox ESR 115.43.1, Thunderbird 158.0.1, and Thunderbird 153.5.1.
- CVE-2026-113401Medium
A denial-of-service vulnerability exists in the PDF Viewer component. The vulnerability was fixed in Firefox 158.0.1 and Thunderbird 158.0.1.
- CVE-2026-109780Critical
Vulnerability in the DOM: Core & HTML component allows mitigation bypass. This issue was fixed in Firefox 158 and Thunderbird 158.
- CVE-2026-109774Critical
Invalid pointer and undefined behavior in the DOM: Notifications component. Fixed in Firefox 158 and Thunderbird 158.
- CVE-2026-109772Critical
Same-origin policy bypass in the DevTools component. Fixed in Firefox 158 and Thunderbird 158.
- CVE-2026-109755Critical
A vulnerability in the DOM: Content Processes component allows sandbox escape. It was fixed in Firefox 158 and Thunderbird 158.
- CVE-2026-109750Critical
A vulnerability in the DOM: Web Authentication component causes a site isolation issue. It was fixed in Firefox 158 and Thunderbird 158.
- CVE-2026-109745Critical
Sandbox escape due to uninitialized memory in the DOM: Web Serial component. It was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.
- CVE-2026-109740Critical
Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component. The flaw was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.
Original NVD description (English source)
Same-origin policy bypass in the Networking: Cookies component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS