Vulnerability in Cisco Open Source Snort3

[ Description ]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.

[ Fixes ]Fixes and patches

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ Advisories ]Government CERT advisories

• NCSC-NL22 Oct 2026NCSC-2026-0450

  Vulnerabilities fixed in Snort 3 from Cisco Translated from Dutch

  Probability/damage M/HCVE-2026-20011CVE-2026-20019CVE-2026-20043+10 more CVEs
• BSI CERT-Bund21 Oct 2026WID-SEC-2026-4104

  Cisco products (IOS XE, SFTD) and Snort: Multiple vulnerabilities Translated from German

  Risk highCVE-2026-20236CVE-2026-20011CVE-2026-20356+10 more CVEs

[ References ]References

• sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snort3-m…