Snort
CVE-2026-20066
MEDIUM
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V2 - Validation and Business Logic Resource consumption limits
MITRE ATT&CK
1 technique across 1 tactic: Impact The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Impact | CVSS 5.8 (MEDIUM). Attack vector: Network. Complexity: Low. Privileges required: None. User interaction: None. Exploitation no authentication required. Exploitable via remote/network. |
| Exploit ScenarioDerived | A remote attacker without authentication could exploit this vulnerability to cause a DoS condition when the Snort 3 Detection Engine restarts unexpectedly. |
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Alert meAnalysisAIv1 – Mar 12, 2026
Cisco Snort 3 Detection Engine can be remotely restarted by an unauthenticated attacker through crafted HTTP packets exploiting improper JavaScript normalization in the JSTokenizer logic, causing a denial of service condition that interrupts packet inspection. The vulnerability requires the JSTokenizer feature to be enabled and can be triggered via an established network connection without authentication. No patch is currently available.
Earlier versions of this analysis (1)
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. [CVSS 5.8 MEDIUM]
RemediationAI
Monitor vendor advisories for a patch. Restrict network access to the affected service where possible.
Affects your stack
Find out whether the stacks and servers you run are on an affected version.
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
Classified as CWE-400 (Uncontrolled Resource Consumption). Affects Snort 3 Detection Engine. 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 S
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Severity by source
AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L
Primary rating from Vendor (cisco) · only source for this CVE.
CVSS VectorVendor: cisco
DescriptionCVE.org
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.
Executive ViewAI
CVE-2026-20066 presents moderate security risk, a resource exhaustion vulnerability rated CVSS 5.8. Service availability could be impacted. Organizations should apply vendor updates when available and monitor for exploitation.
Apply vendor patch. If patching is delayed: implement rate limiting and resource quotas.
Threat Intelligence Overview
NVD
CVE.org
EPSS
VulDB
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.
Affected Products (CPE)CVE.org
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GitHub PoC
Exploit-DB