Vulnerability in Cisco Open Source Snort3
CVE-2026-20011
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.8 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
- Cisco Open Source Snort3 — versions 3.1.10.0, 3.1.12.0, 3.1.13.0
- Cisco Secure Firewall Threat Defense (Ftd) Software — versions 10.0.0, 7.0.0, 7.0.0.1
- Cisco Utd Snort Ips Engine Software — versions 16.12.1a, 16.12.2, 16.12.3
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-20011?
- CVE-2026-20011 is a medium-severity vulnerability in Cisco Open Source Snort3, classified under Buffer Access with Incorrect Length Value. CVSS score: 5.8/10. Published 2026-10-21.
- How severe is CVE-2026-20011?
- Medium severity. CVSS v3 base score is 5.8 out of 10.