High severity · published Sep 2, 2026
CVE-2026-66842
BIG-IP and BIG-IQ Configuration utility vulnerability
8.8
CVSS
0.5%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 40% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
BI
BIG-IP · F5
21.1.0 before 21.1.0.1; 21.0.0 before 21.0.0.3; 17.5.0 before 17.5.1.8; 17.1.0 before 17.1.3.4 · source: vendor
BI
BIG-IQ · F5
8.4.0 before 8.4.2.1 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-66842
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-66842
my.f5.com
https://my.f5.com/manage/s/article/K000162521
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