Cisco hit by max severity zero-day exploit targeting Identity Services Engine, so it’s time to patch up

• September 17, 2026

• Cisco fixed critical ISE flaw (CVE‑2026‑76460) allowing unauthenticated API authentication bypass
• Actively exploited; no workarounds exist—patching is the only mitigation, per Cisco PSIRT
• CISA added to KEV catalog, mandating federal agencies patch or disable ISE by Sept 19, 2026

Cisco has fixed a maximum-severity vulnerability found in its Identity Services Engine (ISE) that is being actively exploited in attacks.

ISE is the company’s Network Access Control (NAC) and identity-based policy platform which decides who or what is allowed onto a company’s network, and what they’re allowed to access inside.

“A vulnerability in an API of Cisco Identity Services Engine (ISE) could allow an unauthenticated, remote attacker to bypass authentication,” the company said in a security advisory.

Abused in the wild

“This vulnerability is due to insufficient authentication control on an API endpoint. An attacker could exploit this vulnerability by sending a crafted request to an affected API endpoint. A successful exploit could allow the attacker to gain unauthorized access to the affected device by bypassing the web-based management interface.”

The bug in question is tracked as CVE-2026-76460. It was given a severity score of 10/10 (critical), and was said it affects Cisco ISE and Cisco ISE Passive Identity Connector (ISE-PIC), regardless of device configuration.

In the same advisory, Cisco said its Product Security Incident Response Team (PSIRT) was aware of active exploitation and urged customers to upgrade to a fixed software release as soon as possible. There are no workarounds available for this flaw, and a patch is the only solution. The full list of vulnerable versions and the corresponding patches can be found on this link.

At the same time, the US Cybersecurity and Infrastructure Security Agency (CISA) added the bug to its Known Exploited Vulnerabilities (KEV) catalog, giving Federal agencies a three-day deadline to patch, or stop using ISE entirely. The deadline expires on September 19, 2026.

Cisco has shared Indicators of Compromise (IoC) and advised defenders to hunt for suspicious usernames in access.log files on every node. It also recommended re-imaging nodes and restoring them from backups, in case of a breach.

Via BleepingComputer

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Cisco fixed critical ISE flaw (CVE‑2026‑76460) allowing unauthenticated API authentication bypass Actively exploited; no workarounds exist—patching is the only mitigation, per Cisco PSIRT CISA added to KEV catalog, mandating federal agencies patch or disable ISE by Sept 19, 2026 Cisco has fixed a maximum-severity vulnerability found in its Identity Services…