CVE intelligence and bounded remediation

CVE-2020-3125 — Cisco Asa 5505 Firmware security vulnerability

Critical CVSS 9.8

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.

Severity
Critical
CVSS
9.8 (3.1)
Published
2020-05-06
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-287

Affected products

  • cisco / asa_5505_firmware / 9.10(1.220)
  • cisco / asa_5510_firmware / 9.10(1.220)
  • cisco / asa_5512-x_firmware / 9.10(1.220)
  • cisco / asa_5515-x_firmware / 9.10(1.220)
  • cisco / asa_5520_firmware / 9.10(1.220)
  • cisco / asa_5525-x_firmware / 9.10(1.220)

Showing 6 representative product identities from 17 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Authentication bypass and missing authentication

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Check exposure

  • Map every affected endpoint and protocol path, including alternate ports, legacy routes, recovery flows, service accounts, and machine-to-machine access.
  • Confirm which deployments enable the affected authentication mode and whether the interface is reachable from untrusted networks.
  • Review session, token, credential, and proxy trust configuration without attempting account takeover.

Remediate safely

  • Apply the supported fix and centralize fail-closed authentication before protected request handling.
  • Remove default or embedded credentials, rotate affected secrets and sessions, and bind authentication decisions to the intended audience and channel.
  • Add negative tests for alternate routes, malformed or absent credentials, recovery flows, and proxy-derived identity.

Authoritative sources

Complete CVE record and remediation plan

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