CVE-2026-91147 Cockpit: cockpit: denial of service in `cockpit-ws` due to url-root handling without a trailing slash
Remote unauthenticated attackers can crash the Cockpit web service by sending a specific request when a custom URL root is configured.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-91147?
CVE-2026-91147 is a medium-severity denial of service vulnerability in Red Hat Enterprise Linux 10, published on 18 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A flaw was found in `cockpit-ws`. This vulnerability allows a remote, unauthenticated attacker to cause a Denial of Service (DoS) by sending a specially crafted request. When the `WebService.UrlRoot` is configured and a request is made to the exact URL-root prefix without a trailing slash, `cockpit-ws` can terminate unexpectedly. This issue leads to the unavailability of the Cockpit web service.
Weakness: CWE-617
Which versions are affected by CVE-2026-91147?
How do I fix CVE-2026-91147?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-91147 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-91147 exists.
Sources
Also known as DEBIAN-CVE-2026-91147, GHSA-cj5v-4j3m-m6j5, UBUNTU-CVE-2026-91147.