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CVE-2024-20353

8.6, high Known exploited

Cisco ASA and FTD Denial of Service Vulnerability

NVD (opens in a new tab) CVE.org (opens in a new tab) CISA KEV catalogue (opens in a new tab)
CVSS
8.6, high high CVSS v3.1
EPSS, next 30 days
71% higher than 99.3% of scored CVEs
Exploitation
Confirmed in the wild
Published
24 Apr 20242 years ago

Known exploited

CISA added this to the Known Exploited Vulnerabilities Catalog on 24 Apr 2024. US federal agencies had to remediate by 1 May 2024, a deadline that has passed.

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

Description

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.

Details

Vendor
Cisco
Product
Cisco Adaptive Security Appliance (ASA) Software
Weakness
CWE-835 (opens in a new tab)
Status
Analyzed
Updated
11 Aug 2026
Assigner
psirt@cisco.com

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

References 3

Exploit code 1

Advisories 1

Other references 1

The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.

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  • CVE-2026-20316 Cisco Secure Firewall Management Center Use of Hard-coded Password Vulnerability KEV EPSS 35% 5.3, medium
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Beyond this page

Is CVE-2024-20353 in your network?

This page tells you how dangerous CVE-2024-20353 is out there. Whether it sits on one of your devices, only a scan of your own network can tell. That is what our systems do, every day, for the companies we protect.

CVE-2024-20353 is in the CISA catalogue of exploited vulnerabilities: attackers are already exploiting it.

  • EXYS7600 OCELOT

    Find it before attackers do

    Ocelot scans your network on a schedule and reports every vulnerability it finds by its CVE identifier, with its CVSS score and how many of your hosts are affected. A finding like CVE-2024-20353 comes with the devices to patch.

    Learn more about EXYS7600 OCELOT

  • EXYS7950 KONDRA

    Detect it if it's exploited

    Until the patch is applied, Kondra monitors your network, events and endpoints in real time. It keeps an inventory of the software installed on every endpoint, and its anomaly detection rules flag what an attacker does once inside.

    Learn more about EXYS7950 KONDRA
Check your exposure

Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 17 Oct 2026, not the live upstream state.