CVE-2026-20066
Denial of Service in Cisco Snort 3 via JSTokenizer Flaw
Publication date: 2026-03-04
Last updated on: 2026-03-04
Assigner: Cisco Systems, Inc.
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| cisco | snort_3 | * |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-400 | The product does not properly control the allocation and maintenance of a limited resource. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability affects multiple Cisco products that use the Snort 3 Detection Engine. It is caused by an error in the JSTokenizer normalization logic, which is part of the HTTP inspection process that normalizes JavaScript. An unauthenticated, remote attacker can exploit this by sending specially crafted HTTP packets through an established connection that Snort 3 parses.
Exploiting this vulnerability can cause the Snort 3 Detection Engine to restart unexpectedly, leading to an interruption in packet inspection.
It is important to note that JSTokenizer is not enabled by default.
How can this vulnerability impact me? :
The primary impact of this vulnerability is a Denial of Service (DoS) condition. An attacker can cause the Snort 3 Detection Engine to restart unexpectedly, which interrupts packet inspection.
This interruption could reduce the effectiveness of network security monitoring and intrusion detection, potentially allowing malicious traffic to go undetected during the downtime.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
I don't know
How can this vulnerability be detected on my network or system? Can you suggest some commands?
I don't know
What immediate steps should I take to mitigate this vulnerability?
This vulnerability is due to an error in the JSTokenizer normalization logic, which is not enabled by default.
To mitigate this vulnerability, ensure that JSTokenizer is not enabled if it is not required.
Additionally, monitor for updates or patches from Cisco addressing this issue and apply them promptly to prevent potential denial of service conditions caused by the Snort 3 Detection Engine restarting unexpectedly.