CVE-2025-10859 Data stored in cookies for non-HTML content while browsing Incognito could be viewed after closing private tabs
Attackers can view private browsing data from closed Incognito tabs due to incorrect cookie storage sharing in Firefox for iOS.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2025-10859?
CVE-2025-10859 is a medium-severity vulnerability in Mozilla Firefox, published on 30 Sep 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
Cookie storage for non-HTML temporary documents was being shared incorrectly with normal browsing content, allowing information from private tabs to escape Incognito mode even after the user closed all tabs. This vulnerability was fixed in Firefox for iOS 143.1.
Weakness: CWE-359
Which versions are affected by CVE-2025-10859?
It affects 1 product.
Products include Mozilla Firefox.
How do I fix CVE-2025-10859?
No fix has been published for CVE-2025-10859 yet. Limit exposure of the affected software until one is available.
Is CVE-2025-10859 being exploited?
There is no known exploitation of CVE-2025-10859 in the wild and no public exploit code.
Other vulnerabilities in Mozilla Firefox
Sources
Also known as GHSA-q64v-9mh2-3xcq.