DoS via malformed cert in Cisco IOS XE Web mgmt
CVE-2026-20311 Published on August 5, 2026

Cisco IOS XE Software Web UI Denial of Service Vulnerability
A vulnerability in the web-based management interface of Cisco IOS XE Software could allow an authenticated, remote attacker with low privileges to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to insufficient error handling in the web-based management interface. An attacker could exploit this vulnerability by authenticating with a malformed certificate. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition.

NVD

Vulnerability Analysis

CVE-2026-20311 can be exploited with network access, and requires small amount of user privileges. This vulnerability is consided to have a high level of 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:
HIGH
Privileges Required:
LOW
User Interaction:
NONE
Scope:
CHANGED
Confidentiality Impact:
NONE
Integrity Impact:
NONE
Availability Impact:
HIGH

Weakness Type

Buffer Over-read

The software reads from a buffer using buffer access mechanisms such as indexes or pointers that reference memory locations after the targeted buffer. This typically occurs when the pointer or its index is incremented to a position beyond the bounds of the buffer or when pointer arithmetic results in a position outside of the valid memory location to name a few. This may result in exposure of sensitive information or possibly a crash.


Products Associated with CVE-2026-20311

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Cisco IOS XE
 

Affected Versions

Cisco IOS XE Software: