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CVE-2024-20353

HIGH
8.6
CVSS Score
Published: April 24, 2024 at 06:15 PM UTC
Updated: August 11, 2026 at 07:48 PM UTC
4 products affected across 1 vendorAdaptive Security ApplianceSecure Firewall Threat DefenseASA

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Severity
HIGH8.6
Exploitation
CISA KEV
Exploit prediction
EPSS 70%
SSVC
Active

Actively Exploited

CISA Known Exploited Vulnerabilities (KEV) Catalog

EPSS Score69.8%

EPSS (Exploit Prediction Scoring System) estimates a 69.8% chance this CVE is exploited in the wild within the next 30 days — higher than 99% of all CVEs. It complements CVSS: a high EPSS on a mid-severity CVE can still be urgent.

Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) contain an infinite loop vulnerability that can lead to remote denial of service condition.

Required Action
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Ransomware Use
Unknown
Added to KEV
Apr 24, 2024
Remediation Due
May 1, 2024
908 days overdue
Notes
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-websrvs-dos-X8gNucD2
https://nvd.nist.gov/vuln/detail/CVE-2024-20353

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Adaptive Security Appliance· Cisco
95%
9.12.1 ≤ v ≤ 9.12.4.659.14.1 ≤ v < 9.14.4.239.15.1 ≤ v ≤ 9.15.1.219.16.1 ≤ v ≤ 9.16.4.559.17.1 ≤ v ≤ 9.17.1.339.18.1 ≤ v ≤ 9.18.4.89.19.1 ≤ v ≤ 9.19.1.279.20.1 ≤ v ≤ 9.20.29.8.1 ≤ v ≤ 9.8.4.489.12.19.12.1.29.12.1.39.12.29.12.2.19.12.2.49.12.2.59.12.2.99.12.39.12.3.129.12.3.29.12.3.79.12.3.99.12.49.12.4.109.12.4.139.12.4.189.12.4.29.12.4.249.12.4.269.12.4.299.12.4.309.12.4.359.12.4.379.12.4.389.12.4.399.12.4.49.12.4.409.12.4.419.12.4.479.12.4.489.12.4.509.12.4.529.12.4.549.12.4.559.12.4.569.12.4.589.12.4.629.12.4.659.12.4.79.12.4.89.14.19.14.1.109.14.1.159.14.1.199.14.1.309.14.1.69.14.29.14.2.139.14.2.159.14.2.49.14.2.89.14.39.14.3.19.14.3.119.14.3.139.14.3.159.14.3.189.14.3.99.14.49.14.4.129.14.4.139.14.4.149.14.4.159.14.4.179.14.4.229.14.4.239.14.4.69.14.4.79.15.19.15.1.19.15.1.109.15.1.159.15.1.169.15.1.179.15.1.219.15.1.79.16.19.16.1.289.16.29.16.2.119.16.2.139.16.2.149.16.2.39.16.2.79.16.39.16.3.149.16.3.159.16.3.199.16.3.239.16.3.39.16.49.16.4.149.16.4.189.16.4.199.16.4.279.16.4.389.16.4.399.16.4.429.16.4.489.16.4.559.16.4.99.17.19.17.1.109.17.1.119.17.1.139.17.1.159.17.1.209.17.1.309.17.1.339.17.1.79.17.1.99.18.19.18.1.39.18.29.18.2.59.18.2.79.18.2.89.18.39.18.3.399.18.3.469.18.3.539.18.3.559.18.3.569.18.49.18.4.59.18.4.89.19.19.19.1.129.19.1.189.19.1.229.19.1.249.19.1.279.19.1.59.19.1.99.20.19.20.1.59.20.29.8.19.8.1.59.8.1.79.8.29.8.2.149.8.2.159.8.2.179.8.2.209.8.2.249.8.2.269.8.2.289.8.2.339.8.2.359.8.2.389.8.2.89.8.39.8.3.119.8.3.149.8.3.169.8.3.189.8.3.219.8.3.269.8.3.299.8.3.89.8.49.8.4.109.8.4.129.8.4.159.8.4.179.8.4.209.8.4.229.8.4.259.8.4.269.8.4.299.8.4.39.8.4.329.8.4.339.8.4.349.8.4.359.8.4.399.8.4.409.8.4.419.8.4.439.8.4.449.8.4.459.8.4.469.8.4.489.8.4.79.8.4.8
Affected range stops below 9.14.4.23, so it looks safe — our inference, not a vendor statement
ASA· Cisco
95%
9.12.1 ≤ v ≤ 9.12.4.659.14.1 ≤ v < 9.14.4.239.15.1 ≤ v ≤ 9.15.1.219.16.1 ≤ v ≤ 9.16.4.559.17.1 ≤ v ≤ 9.17.1.339.18.1 ≤ v ≤ 9.18.4.89.19.1 ≤ v ≤ 9.19.1.279.20.1 ≤ v ≤ 9.20.29.8.1 ≤ v ≤ 9.8.4.489.12.19.14.19.15.19.16.19.17.19.18.19.19.19.20.19.8.1
Affected range stops below 9.14.4.23, so it looks safe — our inference, not a vendor statement
Secure Firewall Threat Defense· Cisco
95%
6.2.36.2.3.16.2.3.106.2.3.116.2.3.126.2.3.136.2.3.146.2.3.156.2.3.166.2.3.176.2.3.186.2.3.26.2.3.36.2.3.46.2.3.56.2.3.66.2.3.76.2.3.86.2.3.96.4.06.4.0.16.4.0.106.4.0.116.4.0.126.4.0.136.4.0.146.4.0.156.4.0.166.4.0.176.4.0.26.4.0.36.4.0.46.4.0.56.4.0.66.4.0.76.4.0.86.4.0.96.6.06.6.0.16.6.16.6.36.6.46.6.56.6.5.16.6.5.26.6.76.6.7.16.7.06.7.0.16.7.0.26.7.0.37.0.07.0.0.17.0.17.0.1.17.0.27.0.2.17.0.37.0.47.0.57.0.67.0.6.17.1.07.1.0.17.1.0.27.1.0.37.2.07.2.0.17.2.17.2.27.2.37.2.47.2.4.17.2.57.2.5.17.3.07.3.17.3.1.17.4.07.4.1
Firepower Threat Defense· Cisco
60%
6.2.3 ≤ v ≤ 6.2.3.186.4.0 ≤ v ≤ 6.4.0.176.6.0 ≤ v ≤ 6.6.7.16.7.0 ≤ v ≤ 6.7.0.37.0.0 ≤ v ≤ 7.0.67.1.0 ≤ v ≤ 7.1.0.37.2.0 ≤ v ≤ 7.2.4.17.3.0 ≤ v ≤ 7.3.1.17.4.0 ≤ v ≤ 7.4.16.2.36.4.06.6.06.7.07.0.07.1.07.2.07.3.07.4.0

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (3)

Vendor Advisory
Source: [email protected]
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-websrvs-dos-X8gNucD2
ExploitThird Party Advisory
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
https://blog.talosintelligence.com/arcanedoor-new-espionage-focused-campaign-found-targeting-perimeter-network-devices/
US Government Resource
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-20353

SSVC — Action Prioritization

SSVCActiveAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

8.6HIGHcisco
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-835

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