Cisco IOS/IOS XE HTTP Server DoS via malformed requests
CVE-2026-20125 Published on March 25, 2026

A vulnerability in the HTTP Server feature of Cisco IOS Software and Cisco IOS XE Software Release 3E could allow an authenticated, remote attacker to cause an affected device to reload unexpectedly, resulting in a denial of service (DoS) condition. This vulnerability is due to improper validation of user-supplied input. An attacker could exploit this vulnerability by sending malformed HTTP requests to an affected device. A successful exploit could allow the attacker to cause a watchdog timer to expire and the device to reload, resulting in a DoS condition. To exploit this vulnerability, the attacker must have a valid user account.

NVD

Vulnerability Analysis

CVE-2026-20125 can be exploited with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
LOW
User Interaction:
NONE
Scope:
CHANGED
Confidentiality Impact:
NONE
Integrity Impact:
NONE
Availability Impact:
HIGH

Weakness Type

Improper Handling of Syntactically Invalid Structure

The product does not handle or incorrectly handles input that is not syntactically well-formed with respect to the associated specification.


Products Associated with CVE-2026-20125

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Affected Versions

Cisco IOS: Cisco IOS XE Software: