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Known exploited vulnerability · CISA KEV

CVE-2023-20269: Cisco Adaptive Security Appliance and Firepower Threat Defense Unauthorized Access Vulnerability

Cisco Adaptive Security Appliance and Firepower Threat Defense contain an unauthorized access vulnerability that could allow an unauthenticated, remote attacker to conduct a brute force attack in an attempt to identify valid username and password combinations or establish a clientless SSL VPN session with an unauthorized user.

CVE-2023-20269

Exploited in the wild. Fix this first.

CISA added it to the Known Exploited Vulnerabilities catalog on 2023-09-13: attackers are using it right now. It is known to be used in ransomware campaigns.

CISA KEV
Listed
Added 2023-09-13 · federal fix-by 2023-10-04
EPSS (30 days)
27%
Higher than 98% of CVEs · 2026-11-01
CVSS
No score

What CISA says

Cisco Adaptive Security Appliance and Firepower Threat Defense Unauthorized Access Vulnerability

Apply mitigations per vendor instructions for group-lock and vpn-simultaneous-logins or discontinue use of the product for unsupported devices.

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How to check if you are exposed to CVE-2023-20269

  1. Find every Cisco Adaptive Security Appliance and Firepower Threat Defense 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 below. 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-2023-20269.

US federal agencies had to fix this by 2023-10-04. 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 1,124 days ago

Vendor advisories and fixes

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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