CVE-2026-76439 Cisco Identity Services Engine Event Injection Vulnerability

Medium 5.3 Published 16 Sep 2026 Updated 18 Sep 2026

Unauthenticated attackers can manipulate endpoint posture status by exploiting insufficient authentication on the guest portal interface.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2026-76439?

CVE-2026-76439 is a medium-severity missing authorization vulnerability in Cisco Identity Services Engine, published on 16 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

A vulnerability in the endpoint posture status reporting functionality of the guest portal web application of Cisco ISE could allow an unauthenticated, remote attacker to submit forged posture status events into the endpoint posture pipeline. This vulnerability is due to insufficient authentication on an internal interface that is exposed through the guest portal. An attacker could exploit this vulnerability by sending a crafted request to an affected system. A successful exploit could allow the attacker to manipulate the posture status on the affected system.

Weakness: CWE-306

Which versions are affected by CVE-2026-76439?

It affects 2 products.

Products include Cisco Identity Services Engine, Cisco Identity Services Engine Passive Identity Connector.

How do I fix CVE-2026-76439?

No fix has been published for CVE-2026-76439 yet. Limit exposure of the affected software until one is available.

Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.

Is CVE-2026-76439 being exploited?

There is no known exploitation of CVE-2026-76439 in the wild and no public exploit code.

All Cisco Identity Services Engine vulnerabilities

Sources

Also known as GHSA-ppcr-3wc7-2p22.