Quick answers
- Is CVE-2026-66842 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-66842 being exploited in the wild.
- How severe is CVE-2026-66842?
- High severity, with a CVSS score of 8.8, published 2 September 2026.
- Which products and versions are affected?
- F5 BIG-IP <UNKNOWN>.
- Is there a fix for CVE-2026-66842?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-66842 attacked?
- It is attacked over the network, in a network appliance.
- Am I affected by CVE-2026-66842?
- Check whether you run F5 BIG-IP at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
This is a privilege escalation vulnerability in the BIG-IP Traffic Management User Interface (TMUI). An authenticated user of any role can send a specially crafted request to the TMUI to create new administrative user accounts, bypassing normal role-based access controls. The vulnerability requires network access to the BIG-IP management interface and valid authentication credentials (any user role), but allows immediate privilege escalation to administrative level. An attacker can gain full administrative control of the BIG-IP system, enabling system reconfiguration, policy bypass, or denial of service. Patch status and specific affected versions are not disclosed in this advisory.
Affected products
- F5 BIG-IP <UNKNOWN>
Timeline
- 2026-09-02: disclosed