CVE-2026-76423

Cisco ISE API Authentication Bypass Vulnerability

Public exploit available. Not confirmed exploited in the wild yet. No fix published yet.

CVSS 3.110.0Critical EPSS percentile46th0.6% chance in 30 days CISA KEVNot listedNo confirmed exploitation
Public exploit: 0 sources FixNone yetNo fix or workaround published

Published 2026-09-16Updated 2026-09-17Sources: CVE.org, NVD

NVD CVE.org

What to do

No fixed build or workaround is published yet. Limit exposure and watch for a patch.

Steps

Written by AI from the record

Check whether you run Cisco Identity Services Engine software or Cisco ISE Passive Identity Connector and whether its management API can be reached from outside your management network.
Restrict access to the API immediately: allow only trusted administrator networks and block all unnecessary internet access to management ports.
There is no Cisco fixed version available yet; ask Cisco or your support provider for the remediation release and apply it as soon as it is published.
Review administrator accounts, API activity, and recent configuration changes for anything unexpected.

May need vendor or contractor work

Is your organisation exposed?Request an assessment to establish which checks fit your systems.

What it is

From the CVE record

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.

In plain language

Written by AI from the record

This is a critical flaw in Cisco Identity Services Engine software and Cisco ISE Passive Identity Connector that can let an outsider take administrator control; act urgently, but Cisco has not yet published a fix.

Unauthenticated remote administrative access is possible through insufficient authorization checks in the exposed REST API web service, allowing crafted HTTP requests to read and alter identity and configuration data.

If you're affected

Administrator takeover
Identity data exposure
Configuration tampering
Access-control disruption
Service interruption

What is it

This is a weakness in a management interface used to control identity and access settings. It is like leaving a building’s master-control room accessible through an outside door: an intruder may be able to change who gets access and inspect sensitive records.

Who is affected

This matters to you if you run Cisco Identity Services Engine software, including Cisco ISE Passive Identity Connector, to manage identities or network access. It is especially important if the management API is reachable from the internet or from networks that untrusted users can access.

How urgent is it

A public exploit is available, meaning attackers have a ready-made way to attempt administrator access. Treat this as a red-priority issue: restrict API access now while awaiting Cisco’s fix.

What to do — in detail

Confirm whether Cisco Identity Services Engine software or Cisco ISE Passive Identity Connector is deployed, then identify every interface and firewall rule that exposes its REST API or management services. No affected-version range or fixed release has been provided, so there is no safe target version to name yet.

Until Cisco publishes a remediation, limit API and management access to a dedicated administrator network or VPN, use firewall allow-lists for trusted administrator addresses, and remove any direct internet exposure. Review audit logs for unusual API requests, new or changed administrator accounts, and unexpected changes to identity sources, access policies, or configuration.

A public exploit is available. Cisco has not supplied a patch or workaround in the available findings, and CISA has not assigned a KEV remediation due date because this CVE is not listed in KEV.

Technical context

CVE-2026-76423 is rated CVSS 10.0 (Critical), with network attack vector, low attack complexity, no privileges required, no user interaction, scope change, high confidentiality and integrity impact, and low availability impact. The weakness is CWE-290: insufficient authorization in the exposed REST API web service; crafted HTTP requests can yield administrative access. Public exploit availability is reported. It is not listed in CISA KEV. EPSS is 0.5% at the 45th percentile with a flat trend; this is a predictive signal, not confirmation of active exploitation.

This is a general assessment based on public vulnerability data. It does not account for your specific infrastructure — when in doubt, consult a security specialist.

Exploitation

Where each signal puts this CVE on the scale from published to confirmed exploited.

EPSS46th

Public exploit

CISA KEV

Not in the catalog. CISA has not confirmed exploitation.

Public exploits

0 sources with a proof of concept or module.

Exploit links, PoCs and Metasploit modules after sign-in

EPSS

0.6% chance of exploitation activity in the next 30 days, which ranks it in the 46th percentile of scored CVEs.

Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.

Lifecycle

6 events over 1 day, from the signal feeds we watch.

2026-09-17Record updatedrecord updated
2026-09-16Publishedweakness classified, att&ck mapped, record updated

Affected products

Ciscocommercial · USaka cisco systems inc., cisco systems
- Cisco Identity Services Engine SoftwareNetworking Infrastructure
- Cisco ISE Passive Identity ConnectorNetworking Infrastructure

Technical detail

CVSS 3.1 vector

Open in the CVSS calculator

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:L

Scored 10.0 by NVD.

How it is reached

Attack Vector NetworkExploitable remotely over the network without any special conditions
Attack Complexity LowNo special conditions — the attack can be reliably reproduced
Privileges Required NoneNo authentication required — anyone can exploit this
User Interaction NoneNo user interaction needed — fully automated exploitation

Scope

Scope ChangedThe exploit can affect other components (e.g. sandbox escape, host compromise from VM)

Impact if exploited

Confidentiality HighTotal information disclosure — all data in the component is compromised
Integrity HighTotal loss of integrity — attacker can modify any data in the component
Availability LowReduced performance or intermittent disruption of service