Used in attacks· fix by 2022-05-037.5High

Cisco Adaptive Security Appliance (ASA)

CVE-2018-0296

Cisco Adaptive Security Appliance (ASA) contains an improper input validation vulnerability with HTTP URLs. Exploitation could allow an attacker to cause a denial-of-service (DoS) condition or information disclosure.

What this means for your business

  • It affects Cisco Adaptive Security Appliance (ASA). 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 3 November 2021.
  • 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 100% 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 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 3 May 2022. 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 updates per vendor instructions.

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:N/I:N/A:H
Weakness
CWE-20
Assigned by
psirt@cisco.com

Dates

Published
2021-11-03
Last modified
2026-08-11
Added to KEV
2021-11-03
Remediation due
2022-05-03
Sources
CISA KEV, NVD

Affected products

  • Cisco Adaptive Security Appliance Software9.1 - 9.1.7.29, 9.2 - 9.2.4.33, 9.3 - 9.4.4.18, 9.5 - 9.6.4.8, 9.7 - 9.7.1.24, 9.8 - 9.8.2.28, 9.9 - 9.9.2.1
  • Cisco Firepower Threat Defense6.2.3-85.02, 6.2.3-851
  • Cisco Secure Firewall Threat Defense6.0 - 6.1.0, 6.2.1 - 6.2.2.3, 6.2.3, 6.2.3.1

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

References