CVE-2020-3299: Cisco Secure Firewall Threat Defense

Medium severity, CVSS 5.8. EPSS: 2.3% chance of exploitation in the next 30 days.

Multiple Cisco products are affected by a vulnerability in the Snort detection engine that could allow an unauthenticated, remote attacker to bypass a configured File Policy for HTTP. The vulnerability is due to incorrect detection of modified HTTP packets used in chunked responses. An attacker could exploit this vulnerability by sending crafted HTTP packets through an affected device. A successful exploit could allow the attacker to bypass a configured File Policy for HTTP packets and deliver a malicious payload.

Affected products

• Cisco Secure Firewall Threat Defense: from 6.0.0, before 6.3.0.1 (fixed in 6.3.0.1)
• Snort Snort: before 2.9.13.1 (fixed in 2.9.13.1)

Published 2020-10-21. Last modified 2026-08-11.