High [CVE-2026-66842] 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)
This high-severity F5 advisory covers CVE-2026-66842 affecting BIG-IP, BIG-IQ.
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Summary
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.
Affected products named by the advisory: BIG-IQ.
- BIG-IP 21.1.0 before 21.1.0.1
- BIG-IP 21.0.0 before 21.0.0.3
- BIG-IP 17.5.0 before 17.5.1.8
- BIG-IP 17.1.0 before 17.1.3.4
- BIG-IQ 8.4.0 before 8.4.2.1
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
- 21.1.0.1
- 21.0.0.3
- 17.5.1.8
- 17.1.3.4
- 8.4.2.1
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
Mitigation
Upgrade to a fixed release: 21.1.0.1, 21.0.0.3, 17.5.1.8, 17.1.3.4, 8.4.2.1. That is the remediation for this advisory.
The vendor advisory may list additional interim mitigations or workarounds not captured here — review it before change work.
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
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