CVE-2026-20011
Published on October 21, 2026

Multiple Cisco Products Snort 3 SMTP MIME Denial of Service Vulnerability
Multiple Cisco products are affected by a vulnerability in the Snort 3 SMTP MIME Decoder that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart. This vulnerability is due to a lack of error checking when the MIME fields of the SMTP header are parsed. An attacker could exploit this vulnerability by sending crafted SMTP packets through an established connection to be parsed by Snort 3. A successful exploit could allow the attacker to cause a denial of service (DoS) condition when the Snort 3 Detection Engine unexpectedly restarts.

NVD

Vulnerability Analysis

CVE-2026-20011 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

Buffer Access with Incorrect Length Value

The software uses a sequential operation to read or write a buffer, but it uses an incorrect length value that causes it to access memory that is outside of the bounds of the buffer. When the length value exceeds the size of the destination, a buffer overflow could occur.


Affected Versions

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