Used in attacks· fix by 2024-03-077.5HighUsed by ransomware gangs

Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD)

CVE-2020-3259

Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) contain an information disclosure vulnerability. An attacker could retrieve memory contents on an affected device, which could lead to the disclosure of confidential information due to a buffer tracking issue when the software parses invalid URLs that are requested from the web services interface. This vulnerability affects only specific AnyConnect and WebVPN configurations.

What this means for your business

  • It affects Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD). It matters if your company, or a supplier that handles your data, runs it.
  • Attackers are already using it. CISA added it to its list of flaws used in real attacks on 15 February 2024.
  • Ransomware gangs are known to have used it.
  • An attacker can use it remotely, over a network, without a login, and without anyone at your company clicking anything.
  • FIRST's prediction model gives it a 72% chance of attack attempts being seen in the next 30 days, ranking above 99% of all known flaws.

What to do

  1. 1Check whether your company or your suppliers run Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD), and which version. The affected versions are listed further down this page.
  2. 2If you do, apply the vendor's fix. A patch or vendor advisory has been published.
  3. 3Treat it as urgent. US federal agencies must fix it by 7 March 2024. That deadline does not apply to private companies, but it shows how seriously CISA takes it.
  4. 4Because attackers have used it, check the affected systems for signs of a break-in, not only for the update.

Not sure if your company is exposed?

Fastnexa’s certified penetration testers can check whether attackers could use this flaw, or others like it, against your websites, apps and network. The full test is free for our first 10 founding clients until 31 December 2026.

Required action

Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

CISA’s wording, unedited.

Scoring

CVSS
7.5 (v3.1)
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Weakness
CWE-200
Assigned by
psirt@cisco.com

Dates

Published
2024-02-15
Last modified
2026-08-12
Added to KEV
2024-02-15
Remediation due
2024-03-07
Sources
CISA KEV, NVD

Affected products

  • Cisco Secure Firewall Threat Defense6.2.3 - 6.2.3.16, 6.3.0 - 6.3.0.6, 6.4.0 - 6.4.0.9, 6.5.0 - 6.5.0.5
  • Cisco Adaptive Security Appliance Software9.8 - 9.8.4.20, 9.9 - 9.9.2.67, 9.10 - 9.10.1.40, 9.12 - 9.12.3.9, 9.13 - 9.13.1.10

As listed in the NVD configuration data. Not a statement about your estate.

References