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Known exploited vulnerability · CISA KEV

CVE-2020-3452: Cisco ASA and FTD Read-Only Path Traversal Vulnerability

Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) contain an improper input validation vulnerability when HTTP requests process URLs. An attacker could exploit this vulnerability by sending a crafted HTTP request containing directory traversal character sequences to an affected device. A successful exploit could allow the attacker to view arbitrary files within the web services file system on the targeted device.

CVE-2020-3452

Exploited in the wild. Fix this first.

CISA added it to the Known Exploited Vulnerabilities catalog on 2021-11-03: attackers are using it right now.

CISA KEV
Listed
Added 2021-11-03 · federal fix-by 2022-05-03
EPSS (30 days)
over 99.9%
Higher than 99.9% of CVEs · 2026-11-01
CVSS
No score

What CISA says

Cisco ASA and FTD Read-Only Path Traversal Vulnerability

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How to check if you are exposed to CVE-2020-3452

  1. Find every Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) system you or your clients run, including ones exposed to the internet. Those come first: CISA only lists flaws attackers are already using.
  2. Compare each version with the fixed versions in the vendor advisory. Where no fix exists yet, apply the vendor’s mitigation or take the system off the internet.
  3. Run a credentialed vulnerability scan to catch the systems you missed, then check that the next scan no longer reports CVE-2020-3452.

US federal agencies had to fix this by 2022-05-03. Everyone else should treat that deadline as a guide: if it has passed, this is overdue.

Timeline

  1. · Added to CISA's Known Exploited Vulnerabilities catalog
  2. · Fix-by date for US federal agencies, passed 1,643 days ago

Weakness type

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Sources: CISA Known Exploited Vulnerabilities catalog (version 2026.10.30); EPSS data from FIRST.org; CVSS and descriptions from the NIST National Vulnerability Database. Checked 2026-11-01. This product uses the NVD API but is not endorsed or certified by the NVD.

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