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Findings

CVE-2026-20066

Multiple Cisco products are affected by a vulnerability in the Snort 3 Detection Engine that could allow an unauthenticated, remote attacker to cause the Snort 3 Detec…

Published Mar 4, 2026 · updated Aug 19, 2026 · cisco snort

Multiple Cisco products are affected by a vulnerability in the Snort 3 Detection Engine that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart, resulting in an interruption of packet inspection. This vulnerability is due to an error in the JSTokenizer normalization logic when the HTTP inspection normalizes JavaScript. An attacker could exploit this vulnerability by sending crafted HTTP packets through an established connection that is parsed by Snort 3. A successful exploit could allow the attacker to cause a DoS condition when the Snort 3 Detection Engine restarts unexpectedly. JSTokenizer is not enabled by default.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 4, 2026 · NIST NVD

    Detected

    Multiple Cisco products are affected by a vulnerability in the Snort 3 Detection Engine that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart, resulting in an interruption of packet inspection. This vulnerability is due to an error in the JSTokenizer normalization logic when the HTTP inspection normalizes JavaScript. An attacker could exploit this vu

  2. Aug 19, 2026 · NIST NVD

    Updated

    Multiple Cisco products are affected by a vulnerability in the Snort 3 Detection Engine that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart, resulting in an interruption of packet inspection. This vulnerability is due to an error in the JSTokenizer normalization logic when the HTTP inspection normalizes JavaScript. An attacker could exploit this vu

Affected

  • cpe cisco/secure firewall threat defense7.4.0
  • cpe cisco/secure firewall threat defense7.4.1
  • cpe cisco/secure firewall threat defense7.4.1.1
  • cpe cisco/secure firewall threat defense7.4.2
  • cpe cisco/secure firewall threat defense7.4.2.1
  • cpe cisco/secure firewall threat defense7.4.2.2
  • cpe cisco/secure firewall threat defense7.4.2.3
  • cpe cisco/snortversion unspecified
  • cpe cisco/unified threat defense snort intrusion prevention system engine17.2.1r

Sources

  • CVE.orgVulnerability recordCVE-2026-20066

    Official CVE identifier

    cve.org
  • NIST NVDVulnerability recordCVE-2026-20066

    Multiple Cisco products are affected by a vulnerability in the Snort 3 Detection Engine that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart, resulting in an interruption of packet inspection. This vulnerability is due to an err

    nvd.nist.gov

References