CVE-2026-20053 Memory corruption in Cisco Cyber Vision

Medium 5.8 Published 4 Mar 2026 Updated 4 Mar 2026

A remote unauthenticated attacker can crash the Snort 3 Detection Engine by sending crafted VBA data, causing a heap overflow and denial of service.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2026-20053?

CVE-2026-20053 is a medium-severity memory corruption vulnerability in Cisco Secure Firewall Threat Defense, published on 4 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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.

Weakness: CWE-122

Which versions are affected by CVE-2026-20053?

It affects 4 products.

Products include Cisco Cyber Vision, Cisco Secure Firewall Threat Defense, Cisco Snort, Cisco Unified Threat Defense Snort Intrusion Prevention System Engine.

How do I fix CVE-2026-20053?

No fix has been published for CVE-2026-20053 yet. Limit exposure of the affected software until one is available.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2026-20053 being exploited?

There is no known exploitation of CVE-2026-20053 in the wild and no public exploit code.

All Cisco Secure Firewall Threat Defense vulnerabilities

Sources

Also known as GHSA-6wj9-h5wq-gm77.