The advisory covers Red Hat OpenShift Container Platform 4.17.56, which contains fixes for several bugs and security vulnerabilities, notably CVE-2026-12151. This vulnerability in the undici WebSocket client allows a remote attacker to cause unbounded memory growth by streaming numerous small or empty WebSocket continuation frames, bypassing per-frame and cumulative-size validation. The result is memory exhaustion leading to denial of service. The advisory includes updated container images and RPM packages to remediate these issues. Red Hat rates this update as critical and provides detailed instructions for upgrading clusters and inspecting release images. No known exploits in the wild have been reported. The vulnerability is tracked under CWE-770 (Allocation of Resources Without Limits or Throttling) and related CWEs.

The primary impact of CVE-2026-12151 is a denial of service condition caused by unbounded memory growth in the undici WebSocket client. An unauthenticated remote attacker can exploit this by sending numerous small or empty WebSocket frames, exhausting system memory and causing affected applications to become unavailable. This affects Red Hat products using the undici WebSocket client or WebSocketStream API, including OpenShift Container Platform 4.17. No confidentiality or integrity impacts are reported. Other addressed bugs and CVEs in the release improve stability and security but are not detailed here.

Red Hat has released updated container images and RPM packages as part of OpenShift Container Platform 4.17.56 to fix this vulnerability and other issues. Users should upgrade their OpenShift clusters to version 4.17.56 using the official upgrade procedures documented by Red Hat. No alternative mitigations are currently available or meet Red Hat's criteria for ease of use and applicability. The vendor manages remediation through these updates, and users are advised to apply them promptly to mitigate the risk of denial of service.