Medium [CVE-2026-20052] Cisco Secure Firewall Threat Defense Software Snort 3 SSL Memory Management Denial of Service Vulnerability
This medium-severity Cisco advisory covers CVE-2026-20052 affecting Cisco Secure Firewall Threat Defense (FTD) Software 7.4.0, Cisco Secure Firewall Threat Defense (FTD) Software 7.4.1.1, Cisco Secure Firewall Threat Defense (FTD) Software 7.4.2.1.
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Summary
A vulnerability in the memory management handling for the Snort 3 Detection Engine of Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart. This vulnerability is due to a logic error in memory management when a device is performing Snort 3 SSL packet inspection.
An attacker could exploit this vulnerability by sending crafted SSL packets through an established connection to be parsed by the Snort 3 Detection Engine. A successful exploit could allow the attacker to cause a denial of service (DoS) c…
Affected products named by the advisory: Cisco Secure Firewall Threat Defense (FTD) Software 7.4.0; Cisco Secure Firewall Threat Defense (FTD) Software 7.4.1.1; Cisco Secure Firewall Threat Defense (FTD) Software 7.4.2.1; Cisco Secure Firewall Threat Defense (FTD) Software 7.6.0; and 2 more.
- Scope: At the time of publication, this vulnerability affected Cisco devices if they were running a vulnerable release of Cisco Secure FTD Software and the following conditions were met:
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
Mitigation checklist
- There are no workarounds that address this vulnerability.
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
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