Quick answers
- Is CVE-2026-77539 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-77539 being exploited in the wild.
- How severe is CVE-2026-77539?
- Critical severity, with a CVSS score of 9.1, published 26 August 2026.
- Which products and versions are affected?
- Ubiquiti UniFi OS.
- Is there a fix for CVE-2026-77539?
- 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-2026-77539 attacked?
- It is attacked over the network.
- Am I affected by CVE-2026-77539?
- Check whether you run Ubiquiti UniFi OS. 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 an Improper Input Validation vulnerability (CWE-20) in UniFi OS Server that allows command injection. An attacker with network access and high privileges can exploit inadequate input validation to inject and execute arbitrary commands on the host device. The vulnerability requires both network connectivity and elevated privileges as preconditions. Successful exploitation grants arbitrary code execution on the UniFi OS host with the privileges of the running service, allowing complete system compromise.
Affected products
- Ubiquiti UniFi OS
Timeline
- 2026-08-26: disclosed