CVE-2026-20011
Multiple Cisco Products Snort 3 SMTP MIME Denial of Service Vulnerability
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.
Weakness: CWE-805
Affected products
| Vendor | Product | Category | Matched by |
|---|---|---|---|
| Cisco | Cisco Firepower Threat Defense (FTD) Check your version | Firewall / NGFW | cna-assigner |
| Cisco | Cisco UTD SNORT IPS Engine | Threat Detection & Sandbox | cna-assigner |
Vendor-reported products (3)
- Cisco · Cisco Open Source Snort3
- Cisco · Cisco Secure Firewall Threat Defense (FTD) Software
- Cisco · Cisco UTD SNORT IPS Engine Software
Vendor advisory
cisco-sa-snort3-mime-vulns-bkXjcKkt
Multiple Cisco Products Snort 3 SMTP MIME Denial of Service Vulnerability
Cisco’s rating: Medium (advisory CVSS 5.8) · Published Oct 21, 2026
Bug IDs: CSCws62055 , CSCwt04581
The vendor’s rating applies to the whole advisory and can differ from this CVE’s own CVSS severity. Where this comes from