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Vulnerability record · CVE-2020-3125 · published 6 May 2020

CVE-2020-3125: Cisco asa 5505 firmware improper authentication vulnerability

Cisco · Asa 5505 Firmware

A vulnerability in the Kerberos authentication feature of Cisco Adaptive Security Appliance (ASA) Software could allow an unauthenticated, remote attacker to impersonate the Kerberos key distribution center (KDC) and bypass authentication on an affected device that is configured to perform Kerberos authentication for VPN or local device access. The vulnerability is due to insufficient identity verification of the KDC when a successful authentication response is received. An attacker could exploit this vulnerability by spoofing the KDC server response to the ASA device. This malicious response would not have been authenticated by the KDC. A successful attack could allow an attacker to bypass Kerberos authentication.

9.8 CVSS 3.1 Critical EPSS 2.4% · top 16.5% CWE-287 · Improper authentication
9.8CVSS 3.1 base score, v2 6.8
2.4%EPSS exploitation probability, 30 days
NoNot in CISA KEV
13Affected product versions listed by NVD
2References
17 Jun 2026Last modified by NVD

Description

A vulnerability in the Kerberos authentication feature of Cisco Adaptive Security Appliance (ASA) Software could allow an unauthenticated, remote attacker to impersonate the Kerberos key distribution center (KDC) and bypass authentication on an affected device that is configured to perform Kerberos authentication for VPN or local device access. The vulnerability is due to insufficient identity verification of the KDC when a successful authentication response is received. An attacker could exploit this vulnerability by spoofing the KDC server response to the ASA device. This malicious response would not have been authenticated by the KDC. A successful attack could allow an attacker to bypass Kerberos authentication.

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

Affected products

13 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-asa-kerberos-bypass-96Gghe2sS Vendor Advisory
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-asa-kerberos-bypass-96Gghe2sS Vendor Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2020-3125), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.