Cisco Cyber Vision Snort 3 Visual Basic for Applications heap-based overflow

Summaryinfo

A vulnerability identified as critical has been detected in Cisco Cyber Vision, Secure Firewall Threat Defense Software and UTD SNORT IPS Engine Software. The affected element is an unknown function of the component Snort 3 Visual Basic for Applications. This manipulation causes heap-based overflow. This vulnerability is registered as CVE-2026-20053. Remote exploitation of the attack is possible. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in Cisco Cyber Vision, Secure Firewall Threat Defense Software and UTD SNORT IPS Engine Software (affected version not known). Affected by this vulnerability is some unknown functionality of the component Snort 3 Visual Basic for Applications. The manipulation with an unknown input leads to a heap-based overflow vulnerability. The CWE definition for the vulnerability is CWE-122. A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc(). As an impact it is known to affect availability. The summary by CVE is:

Multiple Cisco products are affected by a vulnerability in the Snort 3 VBA feature that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to crash. This vulnerability is due to improper range checking when decompressing VBA data, which is user controlled. An attacker could exploit this vulnerability by sending crafted VBA data to the Snort 3 Detection Engine on the targeted device. A successful exploit could allow the attacker to cause an overflow of heap data, which could cause a DoS condition.

The advisory is shared at sec.cloudapps.cisco.com. This vulnerability is known as CVE-2026-20053 since 10/08/2025. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 05/02/2026).

The vulnerability scanner Nessus provides a plugin with the ID 311459 (Multiple Cisco Products Snort 3 VBA Decompression DoS (cisco-sa-ftd-snort3-vbavuls-96UcVVed)), which helps to determine the existence of the flaw in a target environment.

Upgrading eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (311459). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

• Firewall Software

Vendor

• Cisco

Name

• Cyber Vision
• Secure Firewall Threat Defense Software
• UTD SNORT IPS Engine Software

License

• commercial

Website

• Vendor: https://www.cisco.com/

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If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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