CVE-2026-20011: medium-severity vulnerability in Cisco Open Source Snort3
Multiple Cisco Products Snort 3 SMTP MIME Denial of Service Vulnerability
Published · Updated
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13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 5.8epss 0.5%
Multiple Cisco products are affected by a vulnerability in the Snort 3 SMTP MIME Decoder that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart.
This vulnerability is due to a lack of error checking when the MIME fields of the SMTP header are parsed. An attacker could exploit this vulnerability by sending crafted SMTP packets through an established connection to be parsed by Snort 3. A successful exploit could allow the attacker to cause a denial of service (DoS) condition when the Snort 3 Detection Engine unexpectedly restarts.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L
Affected products
Cisco · Cisco Open Source Snort3Cisco · Cisco Secure Firewall Threat Defense (FTD) SoftwareCisco · Cisco UTD SNORT IPS Engine SoftwareRelated CVEs — Cisco Open Source Snort3
In the same product, most dangerous first.
CVE-2025-20362MEDIUMCVE-2025-20362EPSS 87.1%KEVCVE-2025-20333CRITICALCVE-2025-20333EPSS 71.2%KEVCVE-2026-20349HIGHCisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Remote Access SSL VPN Denial of Service VulnerabilityEPSS 1.0%KEVCVE-2026-76418HIGHCisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Remote Access SSL VPN Tunnel Denial of Service VulnerabilityEPSS 0.8%KEVCVE-2021-1285HIGHMultiple Cisco Products SNORT Ethernet Frame Decoder Denial of Service VulnerabilityEPSS 2.9%CVE-2022-20685HIGHMultiple Cisco Products Snort Modbus Denial of Service VulnerabilityEPSS 1.5%