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8.7

F5 BIG-IP allows any signed‑in user to create admin accounts

CVE-2026-66842 · published 2 months ago
Summary

The BIG-IP and BIG-IQ management interfaces let any user who can log in, no matter their role, create new administrative accounts. This could let an attacker who has network access to the management console gain full control of the system. Apply the latest vendor updates and limit access to the management UI to trusted personnel only.

What to do
  • Update f5 big-ip to version 21.1.0.1 or later.
  • Update f5 big-iq to version 8.4.2.1 or later.
Affected software
VendorProductAffected versions
f5 big-ip < 21.1.0.1
f5 big-iq < 8.4.2.1
Original advisory text
BIG-IP has a vulnerability where an authenticated user of any role may be able to create administrative user accounts through an undisclosed request to Traffic Management User Interface (TMUI). ...
BIG-IP has a vulnerability where an authenticated user of any role may be able to create administrative user accounts through an undisclosed request to Traffic Management User Interface (TMUI).




Impact:

This vulnerability may allow an authenticated attacker with network access to the BIG-IP management interface to escalate privileges by creating administrative accounts on the BIG-IP system. There is no data plane exposure; this is a control plane issue only.




Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
References
Fix within
Internet-facing 14 days
Internal At next upgrade
  • Not known to be exploited
  • Needs hands-on effort to exploit
  • Gives an attacker full control
Severity
8.7 High
Exploitation
<1% chance of attack within 30 days
Type
CWE-918Server-Side Request Forgery (SSRF)
Timeline
Published2 Sep 2026
Updated4 Nov 2026
First seen2 Sep 2026
Sources
CVE-2026-66842 · NVD
CVE-2026-66842 · MITRE
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