CVE-2026-91149

Cockpit: cockpit: denial of service via unbounded connection thread spawning

Published Sep 18, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
Description
A flaw was found in Cockpit. An unauthenticated remote attacker can exploit this vulnerability by initiating and sustaining numerous simultaneous connections to the `cockpit-tls` service. This forces the service to create an unbounded number of detached threads, consuming system resources such as memory and file descriptors. The primary consequence is a denial of service (DoS), leading to degradation or complete unavailability of the Cockpit service for legitimate users.

Remediation

Vendor Workaround

Restrict network access to the Cockpit listener (TCP port 9090) to trusted management networks or localhost only, using host firewall rules such as firewalld zones or iptables rules that limit which sources may reach port 9090. If remote access to the Cockpit web console is not required, disable the listener entirely with `systemctl disable --now cockpit.socket`. External connection-rate or concurrency limits in front of TCP port 9090, such as those enforced by a firewall or reverse proxy, further reduce exploitability. Lowering the service's task or file-descriptor ceilings can reduce the blast radius, but does not correct the missing concurrency bound in the cockpit-tls accept path; fixes are being pursued for the affected product streams.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
CPEs cpe:/o:redhat:enterprise_linux:10.3
References
Type Values Removed Values Added
CPEs cpe:/a:redhat:enterprise_linux:10 cpe:/o:redhat:enterprise_linux:10.2
References
Type Values Removed Values Added
First Time appeared Redhat rhel Els
CPEs cpe:/o:redhat:enterprise_linux:10
cpe:/o:redhat:enterprise_linux:7
cpe:/o:redhat:enterprise_linux:8
cpe:/a:redhat:enterprise_linux:10
cpe:/a:redhat:enterprise_linux:8
cpe:/o:redhat:rhel_els:7
Vendors & Products Redhat rhel Els
Type Values Removed Values Added
CPEs cpe:/o:redhat:enterprise_linux:9 cpe:/a:redhat:enterprise_linux:9::appstream
cpe:/o:redhat:enterprise_linux:9::baseos
References
Type Values Removed Values Added
First Time appeared Redhat openshift Dev Spaces
Vendors & Products Redhat openshift Dev Spaces
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description A flaw was found in Cockpit. An unauthenticated remote attacker can exploit this vulnerability by initiating and sustaining numerous simultaneous connections to the `cockpit-tls` service. This forces the service to create an unbounded number of detached threads, consuming system resources such as memory and file descriptors. The primary consequence is a denial of service (DoS), leading to degradation or complete unavailability of the Cockpit service for legitimate users.
Title Cockpit: cockpit: denial of service via unbounded connection thread spawning
First Time appeared Redhat
Redhat enterprise Linux
Redhat openshift Devspaces
Weaknesses CWE-770
CPEs cpe:/a:redhat:openshift_devspaces:3
cpe:/o:redhat:enterprise_linux:10
cpe:/o:redhat:enterprise_linux:7
cpe:/o:redhat:enterprise_linux:8
cpe:/o:redhat:enterprise_linux:9
Vendors & Products Redhat
Redhat enterprise Linux
Redhat openshift Devspaces
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
redhat
Published
Updated
Nov 11, 2026, 5:45 PM
Reserved
Sep 14, 2026, 8:36 PM
Status
Awaiting Analysis
Published
Sep 18, 2026, 5:17 PM
Modified
Nov 11, 2026, 6:19 PM
Severity
Important
Public date
Sep 18, 2026, 4:28 PM