Vulnerability · Published Oct 21, 2026 · Assigned by cisco
CVE-2026-20011Multiple Cisco Products Snort 3 SMTP MIME Denial of Service Vulnerability
Medium 5.8
In plain English
A medium-severity security flaw in Cisco Open Source Snort3 from Cisco. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 45% of all known vulnerabilities).
Official 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 (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Cisco | Cisco Open Source Snort3 | 3.1.2.03.1.3.03.1.4.03.1.5.03.1.6.03.1.7.03.1.8.03.1.9.0 |
| Cisco | Cisco Secure Firewall Threat Defense (FTD) Software | 7.0.07.0.0.17.0.17.0.1.17.0.27.2.07.0.2.17.0.3 |
| Cisco | Cisco UTD SNORT IPS Engine Software | 3.17.1S16.12.3Fuji-16.9.516.12.417.3.1a16.6.616.12.2Fuji-16.9.6 |
Weakness: CWE-805 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L