ZeroHour

CVE-2026-76423

large1

Unauthenticated Administrative Access via REST API Flaw in Cisco ISE and ISE-PIC

CVSS 3.1
10.0 critical
EPSS
Published
()
Modified
AI analysis

Cisco ISE and Cisco ISE-PIC contain an authentication bypass (CWE-290) in their REST API web service, which is exposed with insufficient authorization checks. An unauthenticated, remote attacker can exploit it by sending a crafted HTTP request to the exposed REST API port, requiring no credentials or user interaction. A successful exploit grants administrative privileges over the device, letting the attacker read and modify ISE configuration and identity data. Any organization running an affected Cisco ISE or ISE-PIC deployment is affected, with risk highest where the REST API port is reachable from untrusted networks. No public proof-of-concept or in-the-wild exploitation is currently known, and the flaw is not yet listed in CISA's KEV catalog.

What to do: Upgrade ISE and ISE-PIC to the fixed releases identified in the Cisco PSIRT advisory for CVE-2026-76423. As an interim mitigation, restrict network access to the ISE REST API port to trusted management networks and disable the REST API service where it is not required. Review ISE logs for unauthenticated or anomalous administrative API requests, and treat configuration and identity data on exposed deployments as potentially compromised.

Affected
Cisco Identity Services Engine (ISE)
Cisco ISE Passive Identity Connector (ISE-PIC)
Estimated exposure
largeTens of thousands of enterprise/government deployments likely affected; directly internet-exposed REST API instances estimated in the low thousands — Cisco ISE is one of the most widely deployed enterprise NAC/identity platforms, implying a deployment base in the tens of thousands of organizations, but the REST API port is typically kept on internal management networks, so only a small…

Order-of-magnitude estimate by the model from install counts, market share and public scan data it knows; verify before quoting.

Description

A vulnerability in the REST API of Cisco ISE and Cisco ISE-PIC could allow an unauthenticated, remote attacker to gain administrative access to an affected device. This vulnerability is due to the REST API web service being exposed with insufficient authorization checks. An attacker could exploit this vulnerability by sending a crafted HTTP request to the exposed REST API port. A successful exploit could allow the attacker to read and modify ISE configuration and identity data with administrative privileges.

Weakness
CWE-290
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:L

In the news

Cisco Warns of New Zero-Day ISE Auth Bypass (CVSS 10.0) Exploited in Active Attacks

Cisco warns CVE-2026-76460 (CVSS 10.0), an unauthenticated ISE auth bypass leading to root command execution, is under active exploitation and was added to CISA's KEV.

Cisco warned that CVE-2026-76460 (CVSS 10.0), an insufficient-authentication flaw in an Identity Services Engine (ISE) API endpoint, is being actively exploited by unauthenticated remote attackers and can yield root-privilege command execution on ISE and ISE-PIC regardless of configuration. Fixes shipped across ISE 3.1 through 3.5 patch branches; Cisco advised reviewing access.log for unexpected usernames (e.g., "dummyuser"), re-imaging affected nodes, and using iACLs, since no workarounds exist. CISA added the flaw to its KEV catalog on September 16, 2026, requiring FCEB agencies to patch by September 19. Cisco simultaneously issued 77 new CVEs, 41 affecting ISE and 28 affecting Secure Firewall products, days after confirming active exploitation of CVE-2026-76461 in Secure Email Gateway.

Cisco warns of max severity ISE zero-day exploited in attacks

Cisco patched CVE-2026-76460, a maximum-severity authentication bypass in Identity Services Engine actively exploited in attacks; CISA added it to KEV with a three-day federal deadline.

CVE-2026-76460 is a maximum-severity authentication bypass in an API endpoint of Cisco Identity Services Engine (ISE) and ISE-PIC, exploitable regardless of configuration, allowing attackers to access the web-based management interface. Cisco PSIRT confirmed active exploitation; no workarounds exist, and fixed releases are available for ISE 3.1 through 3.5, with re-imaging of suspect nodes recommended. CISA added the flaw to its Known Exploited Vulnerabilities Catalog and ordered federal agencies to patch within three days. Cisco also patched CVE-2026-76423 and five other critical ISE flaws (CVE-2026-20176, CVE-2026-20211, CVE-2026-20307, CVE-2026-20284) that are not yet flagged as exploited.

BleepingComputer · 7h agoExploit / PoC in the wildCVE-2026-76460CVE-2026-76423CVE-2026-20176+4 CVEs1· 1 read