CVE-2026-20067 Multiple Cisco Products Snort 3 TBD Denial of Service Vulnerability
Remote attackers can cause a denial of service by sending crafted HTTP packets that trigger a restart of the Snort 3 detection engine.
- 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-2026-20067?
CVE-2026-20067 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 error checking when parsing the Multicast DNS fields of the HTTP header. An attacker could exploit this vulnerability by sending crafted HTTP packets through an established connection to be parsed by Snort 3. A successful exploit could allow the attacker to cause a DoS condition when the Snort 3 Detection Engine unexpectedly restarts.
Weakness: CWE-787
Which versions are affected by CVE-2026-20067?
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-2026-20067?
No fix has been published for CVE-2026-20067 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-2026-20067 being exploited?
There is no known exploitation of CVE-2026-20067 in the wild and no public exploit code.
Other vulnerabilities in Cisco Secure Firewall Threat Defense
- CVE-2022-20685 Multiple Cisco Products Snort Modbus Denial of Service Vulnerability
- CVE-2026-20005 Denial of service in Cisco Cyber Vision
- CVE-2026-20053 Memory corruption in Cisco Cyber Vision
- CVE-2026-20054 Denial of service in Cisco Cyber Vision
- CVE-2026-20057 Cisco Secure Firewall Threat Defense Software Snort 3 Visual Basic for Application Denial of Service Vulnerability
Sources
Also known as GHSA-mw99-v56m-j965.