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CVE-2024-20353

Exploited in the wild. In CISA KEV since 2024‑04‑24. A vendor fix is available.

CVSS 3.18.6HighEPSS percentile99th71% chance in 30 daysCISA KEVListedsince 2024-04-24, due 2024-05-01
Public exploit: 1 sourceFixVendor fixNo build named by the sources

Published Updated Sources: CVE.org, NVD, BDU

NVD CVE.org

What to do

The vendor has published a fix. Version details are below where the sources state them.

  • Cisco Adaptive Security Appliance SoftwareAffected: 9.8.1Upgrade to: not statedAffected: 9.8.1.5Upgrade to: not statedAffected: 9.8.1.7Upgrade to: not statedAffected: 9.8.2Upgrade to: not stated + 183 more branchesStated by: CVE record
  • Cisco Firepower Threat Defense SoftwareAffected: 6.2.3Upgrade to: not statedAffected: 6.2.3.1Upgrade to: not statedAffected: 6.2.3.2Upgrade to: not statedAffected: 6.2.3.3Upgrade to: not stated + 76 more branchesStated by: CVE record
  • Cisco Systems Inc. Firepower Threat DefenseAffected: 6.2.3Upgrade to: not statedStated by: BDU
  • Cisco Systems Inc. Adaptive Security ApplianceAffected: 9.8.4.22Upgrade to: not statedStated by: BDU

Versions as the sources state them. Full version matrix after sign-in

Check it yourselfA free OpenVAS check exists for this CVE. Run it against your hosts.Is your organisation exposed?Request an assessment to establish which checks fit your systems.

Coverage timeline

0 publishers

  1. Added to CISA KEV catalog

    ·CISA KEV

Sourced from public security reporting — each date is when it was published, not when it happened.

What it is

From the CVE record

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.

In plain language

No plain-language summary for this CVE yet.

Exploitation

Where each signal puts this CVE on the scale from published to confirmed exploited.

EPSS99th
Public exploit
CISA KEV
CISA KEV

Listed as exploited in the wild since 2024-04-24.

US federal agencies must remediate by 2024-05-01.

Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Public exploits

1 source with a proof of concept or module.

Exploit links, PoCs and Metasploit modules after sign-in
EPSS

71% chance of exploitation activity in the next 30 days, which ranks it in the 99th percentile of scored CVEs.

Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.

Lifecycle

The patch came 129 days before any public exploit.

  1. Analysis publishedThe Firewall Crash Bug Cisco Has Now Shipped Twice: CVE-2026-20349 and Its 2024 Twin
  2. Patch availablerecord updated
  3. OpenVAS check added
  4. EPSS band changemoderate → high
  5. Public exploit / PoCsource: other
  6. Patch availablerecord updated

Affected products

Technical detail

CVSS 3.1 vector

Open in the CVSS calculator

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

Scored 8.6 by NVD.

How it is reached

  • Attack Vector NetworkExploitable remotely over the network without any special conditions
  • Attack Complexity LowNo special conditions — the attack can be reliably reproduced
  • Privileges Required NoneNo authentication required — anyone can exploit this
  • User Interaction NoneNo user interaction needed — fully automated exploitation

Scope

  • Scope ChangedThe exploit can affect other components (e.g. sandbox escape, host compromise from VM)

Impact if exploited

  • Confidentiality NoneNo confidentiality impact
  • Integrity NoneNo integrity impact
  • Availability HighTotal denial of service — the component is completely unavailable

Weaknesses

ATT&CK techniques

Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.

Sources

References in the record

And 3 more references. See all after sign-in

Analysis on the cve.tools blog

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We'll flag the next CVE, public exploit or patch for Cisco, not every advisory. This one: actively exploited.