Red Hat Security Advisory: OpenShift Container Platform 4.21.20 bug fix and security update
Affects Red HatSource GCVE Database
Not known to be exploited · CVSS 9.8 Critical · fixed in Red Hat package updates : patch Red Hat as a priority.
Data as of 30 Oct 2026, 11:52 UTC
- EPSS
- 0.6% chance of exploitation in 30 days – higher than 52% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in ea9f65b27c8404e164848ebff1443310fd187629, d6621f60192fe10c047a4487be42a6f4c150707f, a0c4ce9900a108eaf55d0f3b399cb55999647d39 +5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 1 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 30 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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AI-suggested
A fix is available in Red Hat OpenShift Container Platform 4.21.20. Users should upgrade to this version using the OpenShift CLI (oc) or web console as soon as the update is available in their release channel. Detailed upgrade instructions are provided by Red Hat in their official documentation. No additional mitigation steps are indicated beyond applying the update.
Description
Red Hat OpenShift Container Platform 4.21.20 includes a critical security update addressing a kernel vulnerability identified as CVE-2026-43037. The flaw involves the ip6_tunnel component where the skb2->cb[] field was not cleared in the ip4ip6_err() function. This update fixes the issue to prevent potential security risks. Users of OpenShift Container Platform 4.21 are strongly advised to upgrade to this release to mitigate the vulnerability.
References
- access.redhat.com/errata/RHSA-2026:25186 (opens in a new tab)
- access.redhat.com/security/updates/classification/ (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2464351 (opens in a new tab)
- issues.redhat.com/browse/OCPBUGS-77049 (opens in a new tab)
- security.access.redhat.com/data/csaf/v2/advisories/2026/rhsa-2026_25186.json (opens in a new tab)