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VulnerabilityPublished

CVE-2026-40435: F5 BIG-IP · Unprotected Alternate Channel

Affects F5 BIG-IPSource CVE Database V5

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Not known to be exploited · CVSS 5.3 Medium : upgrade to 17.5.1.4 or 17.1.3.1 when convenient.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
5.3Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 13% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 17.5.1.4, 17.1.3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

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 F5 BIG-IP to 17.5.1.4 or 17.1.3.1.

Affected software

ProductAffectedFixed in
F5BIG-IPAffected
  • >=17.5.0 <17.5.1.4
  • >=17.1.0 <17.1.3.1
  • >=16.1.0
Fixed in
  • 17.5.1.4
  • 17.1.3.1

AI-suggested

If you cannot patch yet, review and tighten network access controls and monitor for unexpected connections. Avoid relying solely on IP-based restrictions for critical access control enforcement.

Description

When configured, IP-based access restrictions for httpd do not cover all endpoints, which may allow connections from blocked addresses. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

References

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