What’s Vulnerable › Vulnerabilities
CVE-2026-20011: Multiple Cisco Products Snort 3 SMTP MIME Denial of Service Vulnerability
- Severity: medium (CVSS 5.8 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.5% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-10-21 · updated 2026-10-22
- Weakness: CWE-805
Description
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.
Affected products
- Cisco Open Source Snort3: 3.1.2.0, 3.1.3.0, 3.1.4.0, 3.1.5.0, 3.1.6.0, 3.1.7.0 (+94)
- Cisco Firepower Threat Defense Software: 7.0.0, 7.0.0.1, 7.0.1, 7.0.1.1, 7.0.2, 7.2.0 (+53)
- Cisco UTD SNORT IPS Engine Software: 3.17.1S, 16.12.3, Fuji-16.9.5, 16.12.4, 17.3.1a, 16.6.6 (+101)
In the news
- Multiple Cisco Products Snort 3 SMTP MIME Denial of Service Vulnerability
- Cisco Advance Notification for Publication of October 21, 2026, Security Advisories
References
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