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5.8
Cisco Products: Snort 3 Restart Vulnerability via Malicious HTTP Packets
CVE-2026-20066
Summary
Some Cisco products that use Snort 3 have a security issue that could be exploited by an attacker to shut down the product's ability to inspect traffic, causing disruptions. This is not a problem with the default settings, but it could be triggered by a malicious attack. Cisco is working to resolve this issue, and users are advised to wait for a fix before taking any action.
Original title
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, result...
Original description
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.
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.
nvd CVSS3.1
5.8
Vulnerability type
CWE-400
Uncontrolled Resource Consumption
Published: 4 Mar 2026 · Updated: 13 Mar 2026 · First seen: 6 Mar 2026