Auth bypass in Cisco Identity Services Engine Software
CVE-2026-76439
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.
Vulnerability class: Broken Authentication
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.
EPSS exploit prediction
EPSS: 0.004 (32.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 33rd percentile — 32.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.001
Affected products
- Cisco Identity Services Engine Software — versions 3.1.0, 3.1.0 p1, 3.1.0 p10
- Cisco Ise Passive Identity Connector — versions 3.1.0, 3.2.0, 3.3.0
- Cisco Identity Services Engine — versions 3.3.0, 3.4.0, 3.5.0
- Cisco Identity Services Engine Passive Connector — versions 3.3.0, 3.4.0
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-76439?
- CVE-2026-76439 is a medium-severity vulnerability in Cisco Identity Services Engine Software, classified under Missing Authentication for Critical Function. CVSS score: 5.3/10. Published 2026-09-16.
- How severe is CVE-2026-76439?
- Medium severity. CVSS v3 base score is 5.3 out of 10.