Red Hat Security Advisory: OpenShift Container Platform 4.21.40 security and extras update
Affects Red HatSource GCVE Database
Not known to be exploited · CVSS 7.5 High · fixed in Red Hat package updates : patch Red Hat http2 soon.
Data as of 30 Oct 2026, 00:00 UTC
- Patch
- Available – fixed in 0.53.0, 1.26.3, 1.25.10
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 7 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Upgrade golang.org/x/net/http2 to 0.53.0; net/http to 1.26.3 or 1.25.10.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| golang.org/x/netgolang.org/x/net/http2 | Affected
| Fixed in
|
| Go standard librarynet/http | Affected
| Fixed in
|
| Go standard librarynet/http | Affected
| Fixed in
|
Gogolang.org/x/net/http2pkg:golang/golang.org/x/net/http2Other threats | Affected
| Fixed in– |
Gogolang.org/x/net/http2pkg:golang/golang.org/x/net/http2Other threats | Affected
| Fixed in
|
Gonet/httppkg:golang/net/httpOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A fix is available in Red Hat OpenShift Container Platform version 4.21.40. Users should upgrade to this version using the OpenShift CLI or web console as soon as the updated packages and container images are available in their release channel. Follow Red Hat's official upgrade documentation to fully apply the update. No additional mitigations are specified or required beyond applying the official update.
Description
Red Hat OpenShift Container Platform 4.21.40 includes a security update addressing a denial of service vulnerability in the Go HTTP/2 implementation. The flaw (CVE-2026-33814) involves processing a malformed SETTINGS_MAX_FRAME_SIZE frame, which can cause service disruption. Users of OpenShift Container Platform 4.21 are advised to upgrade to the updated packages and container images to mitigate this issue.