What is CVE-2024-20353?
A vulnerability in the management and VPN web servers for Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker 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. An attacker could exploit this vulnerability by sending a crafted HTTP request to a targeted web server on a device. A successful exploit could allow the attacker to cause a DoS condition when the device reloads.
The record classifies CVE-2024-20353 under weakness class CWE-835. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on availability. 2 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 904 days ago.
Severity and exploitation probability
- CVSS v3.1 base score
- 8.6 — HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H - EPSS (FIRST)
- 70.6% probability of exploitation in the next 30 days, higher than 99.3% of all scored CVEs
- CISA KEV
- Listed since 2024-04-24, federal remediation deadline 2024-05-01
- Threadlinqs priority
- 9/10 — CISA KEV-listed, which Threadlinqs floors at 9
- Published
- 2024-04-24, last modified 2025-10-21
Is CVE-2024-20353 being exploited?
CISA added CVE-2024-20353 to the Known Exploited Vulnerabilities catalog on 2024-04-24, which means the agency holds evidence of exploitation in the wild; US federal civilian agencies had to remediate it by 2024-05-01 under BOD 22-01. Weaponised exploit code for CVE-2024-20353 is publicly available. 1 public proof-of-concept repository is tracked for this identifier. It currently carries a trending score of 48 in the Threadlinqs vulnerability feed.
- trickest/cve (trickest)
Affected products and versions
- Cisco: Adaptive Security Appliance (ASA) Software, Firepower Threat Defense Software
How to fix CVE-2024-20353
Because CVE-2024-20353 is KEV-listed, US federal civilian agencies were required to apply the vendor fix, or stop using the product, by 2024-05-01. No vendor patch reference has been recorded for CVE-2024-20353 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.
Threat activity tracking CVE-2024-20353
1 tracked threat in the Threadlinqs corpus references CVE-2024-20353, either in the campaign’s CVE list or as an indicator on the campaign record.
Sources
Enriched from CVE.org, FIRST EPSS, CISA KEV, GitHub Security Advisories, public proof-of-concept repositories. Last verified by Threadlinqs on .