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CVE-2026-20066

MEDIUM · CVSS 5.8EPSS 0.5%EU EUVD

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.

Key facts

CVSS score
5.8 (v3.1)
Severity
MEDIUM
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L
Weakness (CWE)
CWE-400
EPSS score
0.5% (39th percentile)
In CISA KEV
No
In EU EUVD
Yes (EUVD-2026-9465)
Published
March 4, 2026
NVD last modified
August 19, 2026
Status
Analyzed

EU Vulnerability Database (EUVD)

This vulnerability is also tracked by ENISA as EUVD-2026-9465 in the EU Vulnerability Database. Last updated in EUVD on March 4, 2026.

View on the EU Vulnerability Database

Affected products

  • cisco / secure firewall threat defense
  • cisco / secure firewall threat defense
  • cisco / secure firewall threat defense
  • cisco / secure firewall threat defense
  • cisco / secure firewall threat defense
  • cisco / secure firewall threat defense
  • cisco / secure firewall threat defense
  • cisco / secure firewall threat defense
  • cisco / secure firewall threat defense
  • cisco / secure firewall threat defense
  • cisco / secure firewall threat defense
  • cisco / secure firewall threat defense
  • cisco / secure firewall threat defense
  • cisco / secure firewall threat defense
  • cisco / secure firewall threat defense
  • cisco / secure firewall threat defense
  • cisco / snort
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine
  • cisco / unified threat defense snort intrusion prevention system engine

and 38 more…

Certified products that may be affected

2 FIPS 140 or Common Criteria certified products, from automated matching by sec-certs.org.

References

Last updated September 17, 2026 · Source: NVD, CISA KEV, FIRST.org EPSS

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