CVE-2024-20481: Cisco Adaptive Security Appliance (ASA)…

Should you act?

Exploited: patch now if you run it

CISA has confirmed exploitation in the wild. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

Yes, if you run Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD). CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2024-10-24, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2024-11-14; treat that as the outer limit, not the target.
EPSS 15.9%, percentile 97: FIRST’s model estimates a 15.9% chance of exploitation activity in the next 30 days, higher than 97% of all scored CVEs (very high). EPSS is a probability, not a verdict.
Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.

What it is

A vulnerability in the Remote Access VPN (RAVPN) service of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) of the RAVPN service. This vulnerability is due to resource exhaustion. An attacker could exploit this vulnerability by sending a large number of VPN authentication requests to an affected device. A successful exploit could allow the attacker to exhaust resources, resulting in a DoS of the RAVPN service on the affected device. Depending on the impact of the attack, a reload of the device may be required to restore the RAVPN service. Services that are not related to VPN are not affected. Cisco Talos discussed these attacks in the blog post Large-scale brute-force activity targeting VPNs, SSH services with commonly used login credentials.

CISA’s summary

Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) contain a missing release of resource after effective lifetime vulnerability that could allow an unauthenticated, remote attacker to cause a denial-of-service (DoS) of the RAVPN service.

Weakness type: CWE-772.

Product: Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) · Assigned by: cisco · Published: 2024-10-23

Affected and fixed versions

Vendor	Product	Affected versions (per CVE record)
Cisco	Cisco Adaptive Security Appliance (ASA) Software	9.8.1, 9.8.1.5, 9.8.1.7, 9.8.2, 9.8.2.8, 9.8.2.14, 9.8.2.15, 9.8.2.17, 9.8.2.20, 9.8.2.24, 9.8.2.26, 9.8.2.28
Cisco	Cisco Firepower Threat Defense Software	6.2.3, 6.2.3.1, 6.2.3.2, 6.2.3.3, 6.2.3.4, 6.2.3.5, 6.2.3.6, 6.2.3.7, 6.2.3.8, 6.2.3.10, 6.2.3.11, 6.2.3.9

Severity scores

Scored by	CVSS	Score	Vector
cisco	3.1	5.8 Medium	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L`

Attack vector: network (remotely reachable)
Attack complexity: low
Privileges required: none (no login)
User interaction: none
Scope: changed (can affect other components)

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

CISA KEV: added 2024-10-24; federal due date 2024-11-14. Known ransomware use: Unknown.
CISA required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
CISA SSVC assessment: exploitation active, automatable yes, technical impact partial.
FIRST EPSS (model of 2026-10-21): 15.87% probability of exploitation activity in the next 30 days; percentile 97.

Timeline

2024-10-23 — CVE record published by cisco
2024-10-24 — Added to CISA’s Known Exploited Vulnerabilities catalog
2024-11-14 — CISA remediation deadline for US federal agencies
2025-10-21 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.