CVE-2026-20005 Denial of service in Cisco Cyber Vision

Medium 5.8 Published 4 Mar 2026 Updated 4 Mar 2026

Remote attackers can cause a denial of service in Cisco Snort 3 Detection Engine by sending crafted SSL handshake packets, interrupting packet inspection.

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-2026-20005?

CVE-2026-20005 is a medium-severity denial of service 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 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 parsing of the SSL handshake ingress packets. An attacker could exploit this vulnerability by sending crafted SSL handshake packets. A successful exploit could allow the attacker to cause a denial of service (DoS) condition when the Snort 3 Detection Engine restarts unexpectedly.

Weakness: CWE-392

Which versions are affected by CVE-2026-20005?

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-2026-20005?

No fix has been published for CVE-2026-20005 yet. Limit exposure of the affected software until one is available.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-20005 being exploited?

There is no known exploitation of CVE-2026-20005 in the wild and no public exploit code.

All Cisco Secure Firewall Threat Defense vulnerabilities

Sources

Also known as GHSA-pcm4-9fqw-4w8h.