CVE-2023-20264: A vulnerability in the implementation of Security Assertion Markup Language (SAML) 2.0 single sign-on (SSO) for remote access VPN in Cisco Adaptive Se...

Description

A vulnerability in the implementation of Security Assertion Markup Language (SAML) 2.0 single sign-on (SSO) for remote access VPN in Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to intercept the SAML assertion of a user who is authenticating to a remote access VPN session. This vulnerability is due to insufficient validation of the login URL. An attacker could exploit this vulnerability by persuading a user to access a site that is under the control of the attacker, allowing the attacker to modify the login URL. A successful exploit could allow the attacker to intercept a successful SAML assertion and use that assertion to establish a remote access VPN session toward the affected device with the identity and permissions of the hijacked user, resulting in access to the protected network.

Metrics

CVSS 3.1

6.1/10

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

EPSS Probability

0.38%

29.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-601

Affected Software

Vendor	Product	Versions
Cisco	Adaptive Security Appliance Software	>= 9.18.1, <= 9.18.3.46
Cisco	Adaptive Security Appliance Software	>= 9.19.1.5, <= 9.19.1.12
Cisco	Firepower Threat Defense	7.2.4

References

Timeline

Published: Nov 1, 2023
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2023-20264?

A vulnerability in the implementation of Security Assertion Markup Language (SAML) 2.0 single sign-on (SSO) for remote access VPN in Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to intercept the SAML assertion of a user who is authenticating to a remote access VPN session. This vulnerability is due to insufficient validation of the login URL. An attacker could exploit this vulnerability by persuading a user to access a site that is under the control of the attacker, allowing the attacker to modify the login URL. A successful exploit could allow the attacker to intercept a successful SAML assertion and use that assertion to establish a remote access VPN session toward the affected device with the identity and permissions of the hijacked user, resulting in access to the protected network.

How severe is CVE-2023-20264?

CVE-2023-20264 has a CVSS score of 6.1/10 (MEDIUM severity). The EPSS model estimates a 0.38% probability of exploitation in the next 30 days.

How do I fix CVE-2023-20264?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.