Cisco ASA/Firepower Threat Defense Software infinite loop

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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7.9$0-$5k0.00

Summaryinfo

A vulnerability was found in Cisco ASA and Firepower Threat Defense Software. It has been classified as problematic. This affects an unknown function. This manipulation causes infinite loop. This vulnerability is registered as CVE-2025-20243. Remote exploitation of the attack is possible. No exploit is available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as critical was found in Cisco ASA and Firepower Threat Defense Software (unknown version). Affected by this vulnerability is an unknown code block. The manipulation with an unknown input leads to a infinite loop vulnerability. The CWE definition for the vulnerability is CWE-835. The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop. As an impact it is known to affect availability. The summary by CVE is:

A vulnerability in the management and VPN web servers of Cisco Secure Firewall ASA Software and Secure FTD Software could allow an unauthenticated, remote attacker to cause the device to reload unexpectedly, resulting in a DoS condition. This vulnerability is due to improper validation of user-supplied input on an interface with VPN web services. An attacker could exploit this vulnerability by sending crafted HTTP requests to a targeted web server on an affected device. A successful exploit could allow the attacker to cause a DoS condition when the device reloads.

The advisory is shared at sec.cloudapps.cisco.com. This vulnerability is known as CVE-2025-20243 since 10/10/2024. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/17/2025). MITRE ATT&CK project uses the attack technique T1499 for this issue.

Upgrading eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2025-1839). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

  • Cisco ASA (Adaptive Security Appliance)

Productinfo

Type

Vendor

Name

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.0
VulDB Meta Temp Score: 7.9

VulDB Base Score: 7.5
VulDB Temp Score: 7.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 8.6
CNA Vector (cisco): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Infinite loop
CWE: CWE-835 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Timelineinfo

10/10/2024 CVE reserved
08/14/2025 +308 days Advisory disclosed
08/14/2025 +0 days VulDB entry created
08/17/2025 +3 days VulDB entry last update

Sourcesinfo

Vendor: cisco.com

Advisory: cisco-sa-asaftd-vpn-dos-mfPekA6e
Status: Confirmed

CVE: CVE-2025-20243 (🔒)
GCVE (CVE): GCVE-0-2025-20243
GCVE (VulDB): GCVE-100-320185
CERT Bund: WID-SEC-2025-1839 - Cisco ASA und Secure Firewall Threat Defense: Mehrere Schwachstellen

Entryinfo

Created: 08/14/2025 19:47
Updated: 08/17/2025 08:18
Changes: 08/14/2025 19:47 (63), 08/17/2025 08:18 (7)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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