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CVE-2026-43037VulnerabilityPublished Updated

Red Hat Security Advisory: OpenShift Container Platform 4.21.20 bug fix and security update

Affects Red HatSource GCVE Database

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Authoritative record:CVE-2026-43037· Critical 9.8

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

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
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:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 1 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ c4d3efafcc933fd2ffd169d7dc4f980393a13796, < ea9f65b27c8404e164848ebff1443310fd187629
Fixed in
  • ea9f65b27c8404e164848ebff1443310fd187629
LinuxLinuxAffected
  • ≥ c4d3efafcc933fd2ffd169d7dc4f980393a13796, < d6621f60192fe10c047a4487be42a6f4c150707f
Fixed in
  • d6621f60192fe10c047a4487be42a6f4c150707f
LinuxLinuxAffected
  • ≥ c4d3efafcc933fd2ffd169d7dc4f980393a13796, < a0c4ce9900a108eaf55d0f3b399cb55999647d39
Fixed in
  • a0c4ce9900a108eaf55d0f3b399cb55999647d39
LinuxLinuxAffected
  • ≥ c4d3efafcc933fd2ffd169d7dc4f980393a13796, < 1063515ce15ff31065c4e7f8265f4c2fd3c54876
Fixed in
  • 1063515ce15ff31065c4e7f8265f4c2fd3c54876
LinuxLinuxAffected
  • ≥ c4d3efafcc933fd2ffd169d7dc4f980393a13796, < 590f622669b97eaf7b57a1de7b0a6e68c5d8b2c3
Fixed in
  • 590f622669b97eaf7b57a1de7b0a6e68c5d8b2c3
LinuxLinuxAffected
  • ≥ c4d3efafcc933fd2ffd169d7dc4f980393a13796, < 4a622658f384b03560834cbe8ffcfe69a278f7c8
Fixed in
  • 4a622658f384b03560834cbe8ffcfe69a278f7c8

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

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