CVE-2026-74955 Privilege escalation in the Request Handling component
Attackers can escalate privileges via the Request Handling component in Firefox and Thunderbird, requiring users to upgrade to patched versions.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-74955?
CVE-2026-74955 is a high-severity vulnerability in Mozilla Firefox, published on 18 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
Privilege escalation in the Request Handling component. This vulnerability was fixed in Firefox 154, Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1.
Weakness: CWE-269
Which versions are affected by CVE-2026-74955?
It affects 2 products.
Products include Mozilla Firefox, Mozilla Thunderbird.
How do I fix CVE-2026-74955?
Upgrade to a fixed version.
Is CVE-2026-74955 being exploited?
There is no known exploitation of CVE-2026-74955 in the wild and no public exploit code.
Other vulnerabilities in Mozilla Firefox
Sources
Also known as GHSA-h83v-xrj2-hcmq, UBUNTU-CVE-2026-74955.