CVE
Cockpit: cockpit: denial of service via unbounded fragmented websocket messages
Affects Cockpit deployments whose cockpit-ws WebSocket endpoint is network-reachable, across the listed Red Hat Enterprise Linux 7 to 10 and OpenShift Dev Spaces products. Fixed in version 372.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 372
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 372.
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 35/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Unclear
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
A flaw in Cockpit lets a remote attacker, without logging in, send specially crafted fragmented WebSocket messages that pile up without any total size limit. This exhausts memory and crashes the cockpit-ws service, causing a denial of service in Red Hat Enterprise Linux 7, 8, 9 and 10 and in Red Hat OpenShift Dev Spaces container images that include the cockpit package.
Read the original description
A flaw was found in Cockpit. This vulnerability allows a remote attacker, without prior authentication, to send specially crafted fragmented WebSocket messages. These messages accumulate without a total-size limit, leading to unbounded memory exhaustion and a denial of service in the cockpit-ws service.
Who should check
Teams running Cockpit's cockpit-ws on Red Hat Enterprise Linux systems for remote management, including RHEL 7 to 10 and OpenShift Dev Spaces
Read the source excerpt
“cockpit-ws is often exposed on Red Hat Enterprise Linux systems for remote management”
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure17/25No login or user action needed, reachable over the network without a login · Unknown: Advisories don't say whether default setups are affected
- Reach10/20Shipped in major Linux distributions
- Severity7.5/10CVSS 7.5
- No patch0/5No signal
What would change the score
- Would score about 80 if added to CISA KEV
- Would score about 75 if CISA's SSVC rates exploitation active
- Would score about 40 if advisories confirm default setups are exposed
What to do
Upgrade to a fixed version: 372.
Workaround: Restrict network access to the cockpit-ws WebSocket endpoint to trusted clients until a fix is available.
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
Check whether my systems are affected by CVE-2026-91150 (Cockpit: cockpit: denial of service via unbounded fragmented websocket messages), using the cve.now data below.
Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.
What cve.now has for CVE-2026-91150 (entry last updated 2026-11-11):
Affected:
- Red Hat Red Hat Enterprise Linux 10: version range not reported
- Red Hat Red Hat Enterprise Linux 7: version range not reported
- Red Hat Red Hat Enterprise Linux 8: version range not reported
- Red Hat Red Hat Enterprise Linux 9: version range not reported
- Red Hat Red Hat OpenShift Dev Spaces: version range not reported
- Red Hat Red Hat OpenShift Dev Spaces: version range not reported
- Red Hat Red Hat OpenShift Dev Spaces: version range not reported
Fixed versions: 372.
Conditions (all must be true for the bug to be hit):
- Network reachability to the cockpit-ws WebSocket endpoint (source: https://bugzilla.redhat.com/show_bug.cgi?id=2478436)
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
Attacker needs: network access, no login, no user action.
Workaround: Restrict network access to the cockpit-ws WebSocket endpoint to trusted clients until a fix is available. (source: https://bugzilla.redhat.com/show_bug.cgi?id=2478436)
CISA KEV: CVE-2026-91150 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-91150 only. If you also check another CVE, look up its own KEV status; never assume it from this one.
How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.
Verify against the linked advisories before concluding, and cite the date you read each one:
- https://bugzilla.redhat.com/show_bug.cgi?id=2478436
- https://access.redhat.com/security/cve/CVE-2026-91150
- https://github.com/cockpit-project/cockpit/commit/4bc66ac3e5b4923528f1ac89517a009b7bc90f93
- https://github.com/cockpit-project/cockpit/releases/tag/372
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.
Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.
Entry: https://cve.now/CVE-2026-91150
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-91150"}.Timeline
- CVE published
- First seen by cve.now
Affected versions
- cockpit
Version range not reported
- cockpit
Version range not reported
- cockpit
Version range not reported
- cockpit
Version range not reported
- devspaces/udi-base-rhel10
Version range not reported
- devspaces/udi-base-rhel9
Version range not reported
- devspaces/udi-rhel9
Version range not reported
Evidence 6
CVE record · 2
Establishes: The identifier and description.
- Record
- Record
Write-ups · 1
Establishes: Technical detail and context.
- Report
Other links · 3
- Repository
- Repository
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-91150
Is CVE-2026-91150 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
Cockpit's cockpit-ws WebSocket endpoint accepts fragmented WebSocket messages without a size limit, so a remote client can send messages that cause a denial of service.Source: bugzilla.redhat.com
Am I affected, and how do I check?
The advisory lists Red Hat Enterprise Linux 7, 8, 9 and 10 and Red Hat OpenShift Dev Spaces, with no version ranges given. Check the installed cockpit-ws version (for example with rpm -q cockpit-ws) and whether the cockpit-ws endpoint can be reached over the network.Source: bugzilla.redhat.com
How do I fix CVE-2026-91150?
Update Cockpit to version 372 or later, which contains the upstream fix. Until the update is applied, restrict network access to the cockpit-ws WebSocket endpoint to trusted clients.Source: bugzilla.redhat.com