CVE-2025-20343
CVE-2025-20343 is a high-severity vulnerability in Cisco Identity Services Engine with a CVSS 3.x base score of 8.6. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-697.
Key facts
- Severity: High (CVSS 3.x base score 8.6)
- EPSS exploit prediction: 1% (48th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2025-37893
- Weakness: CWE-697
- Affected product: Cisco Identity Services Engine
- Published:
- Last modified:
Description
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.
Frequently asked questions
- What is CVE-2025-20343?
- 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.
- How severe is CVE-2025-20343?
- CVE-2025-20343 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
- Is CVE-2025-20343 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (48th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2025-20343?
- CVE-2025-20343 primarily affects Cisco Identity Services Engine. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
- How do I fix CVE-2025-20343?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- Does CVE-2025-20343 have an EU (EUVD) identifier?
- Yes. CVE-2025-20343 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-37893.
- When was CVE-2025-20343 published?
- CVE-2025-20343 was published on 2025-11-05 and last updated on 2026-06-17.
References
Affected products (4)
- cpe:2.3:a:cisco:identity_services_engine:3.4.0:-:*:*:*:*:*:*
- cpe:2.3:a:cisco:identity_services_engine:3.4.0:patch1:*:*:*:*:*:*
- cpe:2.3:a:cisco:identity_services_engine:3.4.0:patch2:*:*:*:*:*:*
- cpe:2.3:a:cisco:identity_services_engine:3.4.0:patch3:*:*:*:*:*:*
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