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Fencer Vulns
medium 5.0

CVE-2024-20355 json

A vulnerability in the implementation of SAML 2.0 single sign-on (SSO) for remote access VPN services in Cisco Adaptive Security Appliance…

published 2024-05-22 2 y ago modified 2026-08-11 2 mo ago also EUVD-2024-18070

cvss
5.0
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 26%
public exploits
0
none known

Summary

A vulnerability in the implementation of SAML 2.0 single sign-on (SSO) for remote access VPN services in Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an authenticated, remote attacker to successfully establish a VPN session on an affected device. This vulnerability is due to improper separation of authorization domains when using SAML authentication. An attacker could exploit this vulnerability by using valid credentials to successfully authenticate using their designated connection profile (tunnel group), intercepting the SAML SSO token that is sent back from the Cisco ASA device, and then submitting the same SAML SSO token to a different tunnel group for authentication. A successful exploit could allow the attacker to establish a remote access VPN session using a connection profile that they are not authorized to use and connect to secured networks behind the affected device that they are not authorized to access. For successful exploitation, the attacker must have valid remote access VPN user credentials.

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
2 y ago

Exploit prediction

0.33% chance of exploitation in the next 30 days, higher than 26% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.0 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:N
NVD 3.1 5.0 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:N

Affected products

  • Cisco Cisco Adaptive Security Appliance (ASA) Software
  • Cisco Cisco Firepower Threat Defense Software
  • cisco firepower_management_center
  • cisco adaptive_security_appliance

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.