CVE-2024-20353

Exp

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.

Published: 2024-04-24 Last update: 2025-10-28 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2024-20353 is rated Critical Active Threat (94.3/100): CVSS High severity, with high exploitation likelihood (EPSS 18.83%, 95th percentile). CISA KEV confirms active exploitation (added 2024-04-24) affecting Cisco / Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD). a weakness (CWE-835) Unauthenticated remote administrative access may be possible. EPSS rose +1.46% over the last day, indicating growing attacker interest. The CISA remediation deadline has passed—treat as an emergency patch priority.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

CISA KEV Record for CVE-2024-20353

Name: Cisco ASA and FTD Denial of Service Vulnerability · CISA KEV detail

Exploit added: 2024-04-24

Action due: 2024-05-01

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

Public exploit references (Exploit-DB) for CVE-2024-20353

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2024-20353

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-08 17.38% 18.83% +1.46%
2 2026-05-26 18.83% 17.38% -1.46%
3 2026-05-22 — 18.83% —

Full EPSS history (45 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2024-20353

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.6 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 4.0 [email protected]
8.6 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 4.0 [email protected]

Weakness enumeration for CVE-2024-20353

Affected software / configurations for CVE-2024-20353

Vendor Product Version Raw CPE
cisco adaptive_security_appliance_software 9.8.1 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.1:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.1.5 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.1.5:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.1.7 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.1.7:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.2 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.2:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.2.8 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.2.8:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.2.14 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.2.14:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.2.15 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.2.15:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.2.17 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.2.17:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.2.20 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.2.20:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.2.24 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.2.24:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.2.26 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.2.26:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.2.28 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.2.28:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.2.33 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.2.33:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.2.35 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.2.35:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.2.38 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.2.38:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.3 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.3:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.3.8 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.3.8:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.3.11 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.3.11:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.3.14 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.3.14:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.3.16 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.3.16:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.3.18 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.3.18:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.3.21 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.3.21:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.3.26 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.3.26:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.3.29 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.3.29:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.4 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.4:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.4.3 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.4.3:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.4.7 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.4.7:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.4.8 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.4.8:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.4.10 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.4.10:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.4.12 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.4.12:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.4.15 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.4.15:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.4.17 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.4.17:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.4.20 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.4.20:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.4.22 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.4.22:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.4.25 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.4.25:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.4.26 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.4.26:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.4.29 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.4.29:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.4.32 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.4.32:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.4.33 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.4.33:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.4.34 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.4.34:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.4.35 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.4.35:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.4.39 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.4.39:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.4.40 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.4.40:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.4.41 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.4.41:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.4.43 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.4.43:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.4.44 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.4.44:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.4.45 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.4.45:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.4.46 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.4.46:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.8.4.48 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.8.4.48:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.1 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.1:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.1.2 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.1.2:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.1.3 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.1.3:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.2 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.2:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.2.1 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.2.1:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.2.4 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.2.4:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.2.5 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.2.5:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.2.9 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.2.9:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.3 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.3:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.3.2 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.3.2:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.3.7 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.3.7:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.3.9 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.3.9:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.3.12 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.3.12:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.4 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.4:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.4.2 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.4.2:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.4.4 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.4.4:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.4.7 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.4.7:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.4.8 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.4.8:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.4.10 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.4.10:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.4.13 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.4.13:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.4.18 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.4.18:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.4.24 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.4.24:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.4.26 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.4.26:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.4.29 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.4.29:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.4.30 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.4.30:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.4.35 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.4.35:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.4.37 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.4.37:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.4.38 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.4.38:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.4.39 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.4.39:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.4.40 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.4.40:*:*:*:*:*:*:*
cisco adaptive_security_appliance_software 9.12.4.41 cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.4.41:*:*:*:*:*:*:*

References for CVE-2024-20353

cvelogic Threat Intelligence