CVE-2026-20179
Published on October 21, 2026

Multiple Cisco Products Snort 3 Generic Routing Encapsulation Denial of Service Vulnerabilities
Multiple Cisco products are affected by a vulnerability in the Snort 3 Generic Routing Encapsulation (GRE) Detection Engine that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart, resulting in an interruption of packet inspection. This vulnerability is due to incomplete error checking when Snort 3 parses GRE packets. An attacker could exploit this vulnerability by sending a crafted GRE packet to a targeted device to be parsed by Snort. A successful exploit could allow the attacker to cause the Snort 3 Detection Engine to restart unexpectedly, resulting in a DoS condition.

NVD

Vulnerability Analysis

CVE-2026-20179 can be exploited with network access, and does not require authorization privileges or user interaction. 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 small impact on availability.

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

Weakness Type

Wrap-around Error

Wrap around errors occur whenever a value is incremented past the maximum value for its type and therefore "wraps around" to a very small, negative, or undefined value.


Affected Versions

Cisco Open Source Snort3: Cisco Secure Firewall Threat Defense (FTD) Software: Cisco UTD SNORT IPS Engine Software: