CVE-2026-20011
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Denial of Service in Cisco Snort 3 SMTP MIME Decoder
Vulnerability report for CVE-2026-20011, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-10-21
Last updated on: 2026-10-21
Assigner: Cisco Systems, Inc.
Description
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.
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| Cisco | Cisco | Open Source Snort3 3.1.2.0 |
| Cisco | Cisco | Open Source Snort3 3.1.3.0 |
| Cisco | Cisco | Open Source Snort3 3.1.4.0 |
| Cisco | Cisco | Open Source Snort3 3.1.5.0 |
| Cisco | Cisco | Open Source Snort3 3.1.6.0 |
| Cisco | Cisco | Open Source Snort3 3.1.7.0 |
| Cisco | Cisco | Open Source Snort3 3.1.8.0 |
| Cisco | Cisco | Open Source Snort3 3.1.9.0 |
| Cisco | Cisco | Open Source Snort3 3.1.10.0 |
| Cisco | Cisco | Open Source Snort3 3.1.12.0 |
| Cisco | Cisco | Open Source Snort3 3.1.13.0 |
| Cisco | Cisco | Open Source Snort3 3.1.14.0 |
| Cisco | Cisco | Open Source Snort3 3.1.15.0 |
| Cisco | Cisco | Open Source Snort3 3.1.16.0 |
| Cisco | Cisco | Open Source Snort3 3.1.17.0 |
| Cisco | Cisco | Open Source Snort3 3.1.18.0 |
| Cisco | Cisco | Open Source Snort3 3.1.19.0 |
| Cisco | Cisco | Open Source Snort3 3.1.20.0 |
| Cisco | Cisco | Open Source Snort3 3.1.21.0 |
| Cisco | Cisco | Open Source Snort3 3.1.22.0 |
| Cisco | Cisco | Open Source Snort3 3.1.23.0 |
| Cisco | Cisco | Open Source Snort3 3.1.24.0 |
| Cisco | Cisco | Open Source Snort3 3.1.25.0 |
| Cisco | Cisco | Open Source Snort3 3.1.27.0 |
| Cisco | Cisco | Open Source Snort3 3.1.28.0 |
| Cisco | Cisco | Open Source Snort3 3.1.29.0 |
| Cisco | Cisco | Open Source Snort3 3.1.30.0 |
| Cisco | Cisco | Open Source Snort3 3.1.31.0 |
| Cisco | Cisco | Open Source Snort3 3.1.32.0 |
| Cisco | Cisco | Open Source Snort3 3.1.36.0 |
| Cisco | Cisco | Open Source Snort3 3.1.38.0 |
| Cisco | Cisco | Open Source Snort3 3.1.39.0 |
| Cisco | Cisco | Open Source Snort3 3.1.40.0 |
| Cisco | Cisco | Open Source Snort3 3.1.41.0 |
| Cisco | Cisco | Open Source Snort3 3.1.42.0 |
| Cisco | Cisco | Open Source Snort3 3.1.43.0 |
| Cisco | Cisco | Open Source Snort3 3.1.45.0 |
| Cisco | Cisco | Open Source Snort3 3.1.47.0 |
| Cisco | Cisco | Open Source Snort3 3.1.48.0 |
| Cisco | Cisco | Open Source Snort3 3.1.50.0 |
| Cisco | Cisco | Open Source Snort3 3.1.51.0 |
| Cisco | Cisco | Open Source Snort3 3.1.52.0 |
| Cisco | Cisco | Open Source Snort3 3.1.53.0 |
| Cisco | Cisco | Open Source Snort3 3.1.55.0 |
| Cisco | Cisco | Open Source Snort3 3.1.56.0 |
| Cisco | Cisco | Open Source Snort3 3.1.57.0 |
| Cisco | Cisco | Open Source Snort3 3.1.58.0 |
| Cisco | Cisco | Open Source Snort3 3.1.59.0 |
| Cisco | Cisco | Open Source Snort3 3.1.60.0 |
| Cisco | Cisco | Open Source Snort3 3.1.61.0 |
| Cisco | Cisco | Open Source Snort3 3.1.62.0 |
| Cisco | Cisco | Open Source Snort3 3.1.63.0 |
| Cisco | Cisco | Open Source Snort3 3.1.64.0 |
| Cisco | Cisco | Open Source Snort3 3.1.65.0 |
| Cisco | Cisco | Open Source Snort3 3.1.66.0 |
| Cisco | Cisco | Open Source Snort3 3.1.67.0 |
| Cisco | Cisco | Open Source Snort3 3.1.69.0 |
| Cisco | Cisco | Open Source Snort3 3.1.70.0 |
| Cisco | Cisco | Open Source Snort3 3.1.71.0 |
| Cisco | Cisco | Open Source Snort3 3.1.72.0 |
| Cisco | Cisco | Open Source Snort3 3.1.73.0 |
| Cisco | Cisco | Open Source Snort3 3.1.74.0 |
| Cisco | Cisco | Open Source Snort3 3.1.75.0 |
| Cisco | Cisco | Open Source Snort3 3.1.76.0 |
| Cisco | Cisco | Open Source Snort3 3.1.77.0 |
| Cisco | Cisco | Open Source Snort3 3.1.78.0 |
| Cisco | Cisco | Open Source Snort3 3.1.81.0 |
| Cisco | Cisco | Open Source Snort3 3.1.82.0 |
| Cisco | Cisco | Open Source Snort3 3.1.83.0 |
| Cisco | Cisco | Open Source Snort3 3.1.84.0 |
| Cisco | Cisco | Open Source Snort3 3.2.1.0 |
| Cisco | Cisco | Open Source Snort3 3.2.2.0 |
| Cisco | Cisco | Open Source Snort3 3.3.0.0 |
| Cisco | Cisco | Open Source Snort3 3.3.1.0 |
| Cisco | Cisco | Open Source Snort3 3.3.2.0 |
| Cisco | Cisco | Open Source Snort3 3.3.3.0 |
| Cisco | Cisco | Open Source Snort3 3.3.4.0 |
| Cisco | Cisco | Open Source Snort3 3.3.5.0 |
| Cisco | Cisco | Open Source Snort3 3.3.7.0 |
| Cisco | Cisco | Open Source Snort3 3.5.0.0 |
| Cisco | Cisco | Open Source Snort3 3.5.1.0 |
| Cisco | Cisco | Open Source Snort3 3.8.1.0 |
| Cisco | Cisco | Open Source Snort3 3.6.0.0 |
| Cisco | Cisco | Open Source Snort3 3.6.2.0 |
| Cisco | Cisco | Open Source Snort3 3.9.3.0 |
| Cisco | Cisco | Open Source Snort3 3.7.2.0 |
| Cisco | Cisco | Open Source Snort3 3.7.0.0 |
| Cisco | Cisco | Open Source Snort3 3.9.6.0 |
| Cisco | Cisco | Open Source Snort3 3.10.0.0 |
| Cisco | Cisco | Open Source Snort3 3.7.4.0 |
| Cisco | Cisco | Open Source Snort3 3.9.0.0 |
| Cisco | Cisco | Open Source Snort3 3.5.2.0 |
| Cisco | Cisco | Open Source Snort3 3.6.1.0 |
| Cisco | Cisco | Open Source Snort3 3.9.2.0 |
| Cisco | Cisco | Open Source Snort3 3.6.3.0 |
| Cisco | Cisco | Open Source Snort3 3.9.5.0 |
| Cisco | Cisco | Open Source Snort3 3.7.1.0 |
| Cisco | Cisco | Open Source Snort3 3.9.7.0 |
| Cisco | Cisco | Open Source Snort3 3.7.3.0 |
| Cisco | Cisco | Open Source Snort3 3.9.1.0 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.0.0 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.0.0.1 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.0.1 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.0.1.1 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.0.2 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.2.0 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.0.2.1 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.0.3 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.2.0.1 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.0.4 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.2.1 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.0.5 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.3.0 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.2.2 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.2.3 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.3.1 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.2.4 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.0.6 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.2.5 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.2.4.1 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.3.1.1 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.4.0 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.0.6.1 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.2.5.1 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.4.1 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.2.6 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.0.6.2 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.4.1.1 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.2.7 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.2.5.2 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.3.1.2 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.2.8 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.6.0 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.4.2 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.2.8.1 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.0.6.3 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.4.2.1 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.2.9 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.0.7 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.7.0 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.4.2.2 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.2.10 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.6.1 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.4.2.3 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.0.8 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.6.2 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.7.10 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.7.11 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.0.8.1 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.6.2.1 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.7.10.1 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.4.2.4 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.2.10.2 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.4.3 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.6.4 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 10.0.0 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.4.4 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.0.9 |
| Cisco | Cisco | Secure Firewall Threat Defense (FTD) Software 7.2.11 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 3.17.1S |
| Cisco | Cisco | UTD SNORT IPS Engine Software 16.12.3 |
| Cisco | Cisco | UTD SNORT IPS Engine Software Fuji-16.9.5 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 16.12.4 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.3.1a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 16.6.6 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 16.12.2 |
| Cisco | Cisco | UTD SNORT IPS Engine Software Fuji-16.9.6 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 3.17.0S |
| Cisco | Cisco | UTD SNORT IPS Engine Software Fuji-16.9.3 |
| Cisco | Cisco | UTD SNORT IPS Engine Software Denali-16.3.7 |
| Cisco | Cisco | UTD SNORT IPS Engine Software Fuji-16.9.2 |
| Cisco | Cisco | UTD SNORT IPS Engine Software Fuji-16.9.4 |
| Cisco | Cisco | UTD SNORT IPS Engine Software Everest-16.6.4 |
| Cisco | Cisco | UTD SNORT IPS Engine Software Everest-16.6.3 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 16.6.5 |
| Cisco | Cisco | UTD SNORT IPS Engine Software Denali-16.3.5 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.2.1r |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.1.1 |
| Cisco | Cisco | UTD SNORT IPS Engine Software Everest-16.6.2 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 16.6.7a |
| Cisco | Cisco | UTD SNORT IPS Engine Software Denali-16.3.4 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 16.6.1 |
| Cisco | Cisco | UTD SNORT IPS Engine Software Denali-16.3.9 |
| Cisco | Cisco | UTD SNORT IPS Engine Software Denali-16.3.3 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 16.12.1a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.3.2 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.4.1a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 16.12.5 |
| Cisco | Cisco | UTD SNORT IPS Engine Software Fuji-16.9.7 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 16.6.9 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.3.3 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.5.1a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.3.4a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.4.2 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.4.1b |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.6.1a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 16.6.10 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.7.1a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 16.12.6 |
| Cisco | Cisco | UTD SNORT IPS Engine Software Fuji-16.9.8 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.6.2 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.8.1a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 16.12.7 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.3.5 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.6.3a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.7.2 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.9.1a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.6.4 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.10.1a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.3.6 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 16.12.8 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.3.7 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.9.2a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.6.5 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.11.1a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.9.3a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.12.1a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.9.4 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.6.6 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.3.8 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.12.2 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.13.1a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.9.5a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.12.3 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.6.7 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.14.1a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.12.4 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.12.3a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.15.1a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.9.6 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.6.8a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.16.1a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.9.5e |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.12.4a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.15.2c |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.9.5f |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.12.4b |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.15.2a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.12.5 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.17.1 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.12.5a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.9.7a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.15.3a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.15.3 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.12.5b |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.12.5c |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.15.4 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.9.7b |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.18.1 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.18.1a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.12.6 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.9.8 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.15.4c |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.12.5d |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.18.2 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 26.1.1 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.15.5 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.15.5a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.12.7 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.12.7a |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.12.7b |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.9.9 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.12.8 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.15.6 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 17.18.4 |
| Cisco | Cisco | UTD SNORT IPS Engine Software 26.1.2 |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-805 | The product uses a sequential operation to read or write a buffer, but it uses an incorrect length value that causes it to access memory that is outside of the bounds of the buffer. |
