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VulnerabilityPublished

CVE-2026-42409: F5 BIG-IP · NULL Pointer Dereference

Affects F5 BIG-IPSource CVE Database V5

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Not known to be exploited · CVSS 7.5 High · fixed in 21.0.0.1 : patch F5 BIG-IP soon.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 18% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 21.0.0.1, 17.5.1.4, 17.1.3.1 +4
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 13 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
F5BIG-IPAffected
  • >=21.0.0 <21.0.0.1
  • >=17.5.0 <17.5.1.4
  • >=17.1.0 <17.1.3.1
  • >=16.1.0
Fixed in
  • 21.0.0.1
  • 17.5.1.4
  • 17.1.3.1
F5BIG-IP Next SPKAffected
  • >=2.0.0 <2.0.3
Fixed in
  • 2.0.3
F5BIG-IP Next SPKAffected
  • >=1.7.0 <1.7.17
Fixed in
  • 1.7.17
F5BIG-IP Next CNFAffected
  • >=2.0.0 <2.0.3
Fixed in
  • 2.0.3
F5BIG-IP Next CNFAffected
  • >=1.4.0 <1.4.1
Fixed in
  • 1.4.1
F5BIG-IP Next for KubernetesAffected
  • >=2.0.0 <2.1.1
Fixed in
  • 2.1.1

AI-suggested

If you cannot patch yet, consider avoiding configurations that combine HTTP/2 profiles with iRules using HTTP::redirect or HTTP::respond commands on virtual servers.

Description

When an HTTP/2 profile and an iRule containing the HTTP::redirect or HTTP::respond command are configured on a virtual server, undisclosed requests can cause the Traffic Management Microkernel (TMM) process to terminate. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

References

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