CVE-2024-20353: Cisco ASA and FTD Denial of Service Vulnerability

criticalknown exploitedCVE-2024-20353

Actively exploited. At least one CVE in this advisory is listed in the CISA Known Exploited Vulnerabilities catalog — exploitation has been observed in the wild. Treat remediation as 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.

CSIRTS triage

vendor: Cisco product: Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD)Denial of service

What: The vulnerability can lead to a remote denial of service condition due to an infinite loop.
Who is affected: Deployments of Cisco ASA and FTD are affected.
Urgency: Remediation is urgent as the vulnerability is actively exploited and has critical severity.
Action: Update to the latest version as per Cisco's advisories.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: CISA Known Exploited Vulnerabilities (US · database · site)
Severity: critical
Published: 2024-04-24
Exploitation: Observed in the wild (CISA KEV)

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2024-20353

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Exploitation confirmedCVE-2024-20353Already exploited in the wild (CISA KEV) — the prediction phase is over. Patch now. Riskier than 99.4% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2024-20353	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

unknownexploitedMultiple vulnerabilities in Cisco products (April 25, 2024)cert-fr-alerte

Recent advisories for Cisco ASA and

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

highexploitedAL26-018 - Vulnerability affecting Cisco ASA and Secure Firewall Threat Defense Software Remote Access SSL VPN…cccs · 2026-08-13
unknownexploitedNCSC-2026-0295 [1.00] [M/H] Vulnerability patched in Cisco Secure Firewall ASA and FTD softwarencsc-nl · 2026-08-12
highexploited[NEW] [high] Cisco ASA (Adaptive Security Appliance) and Secure Firewall Threat Defense: Vulnerability enables…cert-bund · 2026-08-12
highexploitedCVE-2026-20349: A vulnerability in the Remote Access SSL VPN service for Cisco Secure Firewall Adaptive Securi…nvd · 2026-08-11
criticalexploitedCVE-2026-20349: Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FT…cisa-kev · 2026-08-11
criticalexploitedCVE-2025-20362: Cisco Secure Firewall Adaptive Security (ASA) Appliance and Secure Firewall Threat Defense (FT…cisa-kev · 2025-09-25

CVE-2024-20353: Cisco ASA and FTD Denial of Service Vulnerability

CSIRTS triage

Details

Exploitation outlook

Referenced CVEs

Same CVEs, other sources

Recent advisories for Cisco ASA and

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