Cisco Snort VBA Decompression Engine stack-based overflow

Summaryinfo

A vulnerability, which was classified as problematic, has been found in Cisco Snort. Affected by this issue is some unknown functionality of the component VBA Decompression Engine. Performing a manipulation results in stack-based overflow. This vulnerability is reported as CVE-2026-20218. The attack is possible to be carried out remotely. No exploit exists. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in Cisco Snort (affected version unknown). It has been classified as problematic. This affects an unknown functionality of the component VBA Decompression Engine. The manipulation with an unknown input leads to a stack-based overflow vulnerability. CWE is classifying the issue as CWE-121. A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function). This is going to have an impact on availability. The summary by CVE is:

A vulnerability in the Snort 3 Visual Basic for Applications (VBA) Decompression Engine of multiple Cisco products could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart unexpectedly, resulting in a denial of service (DoS) condition. This vulnerability is due to improper range checking when Snort 3 decompresses VBA data, which is user controlled. An attacker could exploit this vulnerability by sending crafted VBA data to the Snort 3 Detection Engine of a targeted device. A successful exploit could allow the attacker to cause an overflow of stack data, which could result in a DoS condition.

It is possible to read the advisory at sec.cloudapps.cisco.com. This vulnerability is uniquely identified as CVE-2026-20218 since 10/08/2025. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 10/21/2026).

Upgrading eliminates this vulnerability.

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Productinfo

Vendor

• Cisco

Name

• Snort

License

• commercial

Website

• Vendor: https://www.cisco.com/

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