Cisco Identity Services Engine Radius Suppression Denial of Service Vulnerability
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA.
Summary
A vulnerability in the RADIUS setting Reject RADIUS requests from clients with repeated failures on Cisco Identity Services Engine (ISE) could allow an unauthenticated, remote attacker to cause Cisco ISE to restart unexpectedly. This vulnerability is due to a logic error when processing a RADIUS access request for a MAC address that is already a rejected endpoint. An attacker could exploit this vulnerability by sending a specific sequence of multiple crafted RADIUS access request messages to Cisco ISE. A successful exploit could allow the attacker to cause a denial of service (DoS) condition when Cisco ISE restarts.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Cisco | Cisco Identity Services Engine Software | 3.4.0; 3.4 Patch 1; 3.4 Patch 2; 3.4 Patch 3 | — | No fix listed | CNA |
- Cisco Identity Services Engine Software VendorCisco Affected 3.4.0; 3.4 Patch 1; 3.4 Patch 2; 3.4 Patch 3 Fixed in — No fix listed CNA
CPE configurations NVD · 4
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:cisco:identity_services_engine:3.4.0:-:*:*:*:*:*:* | 3.4.0 | Vulnerable | Cisco |
| cpe:2.3:a:cisco:identity_services_engine:3.4.0:patch1:*:*:*:*:*:* | 3.4.0 patch1 | Vulnerable | Cisco |
| cpe:2.3:a:cisco:identity_services_engine:3.4.0:patch2:*:*:*:*:*:* | 3.4.0 patch2 | Vulnerable | Cisco |
| cpe:2.3:a:cisco:identity_services_engine:3.4.0:patch3:*:*:*:*:*:* | 3.4.0 patch3 | Vulnerable | Cisco |
- cpe:2.3:a:cisco:identity_services_engine:3.4.0:-:*:*:*:*:*:* Versions 3.4.0 Vulnerable ·Cisco
- cpe:2.3:a:cisco:identity_services_engine:3.4.0:patch1:*:*:*:*:*:* Versions 3.4.0 patch1 Vulnerable ·Cisco
- cpe:2.3:a:cisco:identity_services_engine:3.4.0:patch2:*:*:*:*:*:* Versions 3.4.0 patch2 Vulnerable ·Cisco
- cpe:2.3:a:cisco:identity_services_engine:3.4.0:patch3:*:*:*:*:*:* Versions 3.4.0 patch3 Vulnerable ·Cisco
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2025-20343
- 2026-10-03 Alias added: GHSA-cfwq-p5hw-9v6p
References
Advisory 1
More Cisco Identity Services Engine vulnerabilities
- TI-2026-53488 Cisco Identity Services Engine Authentication Bypass Vulnerability KEVCVSS 3.1CRITICAL 10.0
- TI-2025-14632 Cisco ISE API Unauthenticated Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 10.0
- TI-2025-14578 Cisco ISE API Unauthenticated Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 10.0
- TI-2021-19919 Apache Log4j2 JNDI features do not protect against attacker controlled LDAP and other JNDI related endpoints KEVCVSS 3.1CRITICAL 10.0
- TI-2025-14579 Cisco ISE API Unauthenticated Remote Code Execution Vulnerability CVSS 3.1CRITICAL 10.0
- TI-2022-05522 OS command injection in Cisco Identity Services Engine Software CVSS 3.1HIGH 8.8
Sources
- CVE-2025-20343 · CVE Program
- CVE-2025-20343 · NVD
- FIRST EPSS
- GHSA-cfwq-p5hw-9v6p · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences