CVE-2026-20011
Multiple Cisco Products Snort 3 SMTP MIME Denial of Service Vulnerability
- Published
- Updated
- Reserved
- Assigned by
- cisco
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.
Timeline
ID reserved
By cisco
- 13 months later
· 13 months later
Published
- 1 day later
· 1 day later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| ciscoCNA (assigner) | 3.1 | Medium5.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L |
| NVDNVD · Awaiting Analysis | 3.1 | Medium5.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L |
- EPSS (exploitation in 30 days)
- 0.53% · top 55% of all CVEs (7 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.8.
Weakness
Affected products
Cisco · Cisco Open Source Snort3
- affected 3.1.2.0
- affected 3.1.3.0
- affected 3.1.4.0
- affected 3.1.5.0
- affected 3.1.6.0
- affected 3.1.7.0
- affected 3.1.8.0
- affected 3.1.9.0
- affected 3.1.10.0
- affected 3.1.12.0
- affected 3.1.13.0
- affected 3.1.14.0
- affected 3.1.15.0
- affected 3.1.16.0
- affected 3.1.17.0
- affected 3.1.18.0
- affected 3.1.19.0
- affected 3.1.20.0
- affected 3.1.21.0
- affected 3.1.22.0
- affected 3.1.23.0
- affected 3.1.24.0
- affected 3.1.25.0
- affected 3.1.27.0
- affected 3.1.28.0
- affected 3.1.29.0
- affected 3.1.30.0
- affected 3.1.31.0
- affected 3.1.32.0
- affected 3.1.36.0
- affected 3.1.38.0
- affected 3.1.39.0
- affected 3.1.40.0
- affected 3.1.41.0
- affected 3.1.42.0
- affected 3.1.43.0
- affected 3.1.45.0
- affected 3.1.47.0
- affected 3.1.48.0
- affected 3.1.50.0
- and 60 more
Cisco · Cisco Secure Firewall Threat Defense (FTD) Software
- affected 7.0.0
- affected 7.0.0.1
- affected 7.0.1
- affected 7.0.1.1
- affected 7.0.2
- affected 7.2.0
- affected 7.0.2.1
- affected 7.0.3
- affected 7.2.0.1
- affected 7.0.4
- affected 7.2.1
- affected 7.0.5
- affected 7.3.0
- affected 7.2.2
- affected 7.2.3
- affected 7.3.1
- affected 7.2.4
- affected 7.0.6
- affected 7.2.5
- affected 7.2.4.1
- affected 7.3.1.1
- affected 7.4.0
- affected 7.0.6.1
- affected 7.2.5.1
- affected 7.4.1
- affected 7.2.6
- affected 7.0.6.2
- affected 7.4.1.1
- affected 7.2.7
- affected 7.2.5.2
- affected 7.3.1.2
- affected 7.2.8
- affected 7.6.0
- affected 7.4.2
- affected 7.2.8.1
- affected 7.0.6.3
- affected 7.4.2.1
- affected 7.2.9
- affected 7.0.7
- affected 7.7.0
- and 19 more
Cisco · Cisco UTD SNORT IPS Engine Software
- affected 3.17.1S
- affected 16.12.3
- affected Fuji-16.9.5
- affected 16.12.4
- affected 17.3.1a
- affected 16.6.6
- affected 16.12.2
- affected Fuji-16.9.6
- affected 3.17.0S
- affected Fuji-16.9.3
- affected Denali-16.3.7
- affected Fuji-16.9.2
- affected Fuji-16.9.4
- affected Everest-16.6.4
- affected Everest-16.6.3
- affected 16.6.5
- affected Denali-16.3.5
- affected 17.2.1r
- affected 17.1.1
- affected Everest-16.6.2
- affected 16.6.7a
- affected Denali-16.3.4
- affected 16.6.1
- affected Denali-16.3.9
- affected Denali-16.3.3
- affected 16.12.1a
- affected 17.3.2
- affected 17.4.1a
- affected 16.12.5
- affected Fuji-16.9.7
- affected 16.6.9
- affected 17.3.3
- affected 17.5.1a
- affected 17.3.4a
- affected 17.4.2
- affected 17.4.1b
- affected 17.6.1a
- affected 16.6.10
- affected 17.7.1a
- affected 16.12.6
- and 67 more
What to do
Exploitation: The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.
References (1)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-20011)Record last updated .