# CVE-2026-91149: Cockpit: cockpit: denial of service via unbounded connection thread spawning

Status: published. Published: 2026-09-18. Updated: 2026-11-03.

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

- 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. (source: CNA: redhat)

## Affected products and versions

- Red Hat / Red Hat Enterprise Linux 9 (cockpit): ≥ 0:356.4-1.el9_8; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 10 (cockpit): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 (cockpit): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (cockpit): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Dev Spaces (devspaces/udi-base-rhel10): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Dev Spaces (devspaces/udi-base-rhel9): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Dev Spaces (devspaces/udi-rhel9): Version range not reported. Source: CNA: redhat

## Severity and prioritization

- CVSS 3.1: 7.5 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H; source: CNA: redhat

- CISA KEV: No listing in collected sources

- EPSS: 0.35% as of 2026-11-03; percentile 28.38%

- SSVC: exploitation none; automatable yes; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-770

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://access.redhat.com/errata/RHSA-2026:94533 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/security/cve/CVE-2026-91149 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2479422 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-91149; retrieved 2026-11-04; source updated 2026-11-03

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-91149; retrieved 2026-11-04; source updated Not reported

Revision: ede649f52e5313b21fc21d5224b71477f0ad94222ea6b43c310ec162fe0a7d3f

Canonical: https://y2.dev/cve/CVE-2026-91149

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