Cyber Resilience

CVE-2025-20243

HighDDoS

Published: 14 August 2025

Published
14 August 2025
Modified
15 April 2026
KEV Added
Patch
CVSS Score v3.1 8.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
EPSS Score 0.0007 21.3th percentile
Risk Priority 17 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2025-20243 is a high-severity Infinite Loop (CWE-835) vulnerability in Cisco Secure Firewall (inferred from references). Its CVSS base score is 8.6 (High).

Operationally, ranked at the 21.3th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability details

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…

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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.

CWE(s)

Related Threats

No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.

Affected Assets

Cisco
Secure Firewall
inferred from references and description; NVD did not file a CPE for this CVE

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-835

Enables transfer to alternate site if an infinite loop at the primary renders processing unavailable.

addresses: CWE-835

Detects and mitigates infinite loops that produce sustained resource consumption.

References