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Fencer Vulns
high 7.7

CVE-2025-20244 json

Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Remote Access VPN Web Server Denial of Service Vulnerability

published 2025-08-14 14 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-24844

cvss
7.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 46%
public exploits
0
none known

Summary

A vulnerability in the Remote Access SSL VPN service for Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow a remote attacker that is authenticated as a VPN user to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition.

This vulnerability is due to incomplete error checking when parsing an HTTP header field value. An attacker could exploit this vulnerability by sending a crafted HTTP request to a targeted Remote Access SSL VPN service on an affected device. A successful exploit could allow the attacker to cause a DoS condition, which would cause the affected device to reload.

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
14 mo ago

Exploit prediction

0.55% chance of exploitation in the next 30 days, higher than 46% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.7 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H

Affected products

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

Classification

Weakness
  • CWE-1287 Improper Validation of Specified Type of Input

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.