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.
CVE-2026-20066
MEDIUMPre-NVD 5.85.8—Trending — 3 sources updated this week
EchelonGraph scoreMEDIUM confidence
Score 5.8 from GitHub Security Advisory published 2026-03-04. the CNA's CVSS baseline 5.8; sources differ by 0.0.
Triggered by: GitHub Security Advisory CVSS
Sources: cna:cisco, ghsa
5.8EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
- Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.8Exploit: None knownExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 5.8
- EG Score
- 5.8(medium)
- EG Risk
- 41(Track)EG Risk 41/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity58% × 45%Exploitation0% × 40%Automatability100% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- 0%
- EPSS %ILE
- 38%
- KEV
- Not listed
Published
March 4, 2026
Last Modified
June 17, 2026
References (1)
Vendor Advisories for CVE-2026-20066(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 3× in last 7d / 3× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-27 14:13 UTCEPSS rescore
- 2026-07-27 12:54 UTCEG score recompute
- 2026-07-27 12:54 UTCGHSA enrichment
Related CVEs(same CWE)
Same CWE
10 shownCWE-400
Frequently asked(5)
What is CVE-2026-20066?
CVE-2026-20066 is a medium vulnerability published on March 4, 2026. 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…
When was CVE-2026-20066 disclosed?
CVE-2026-20066 was first published in the National Vulnerability Database on March 4, 2026, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-20066 actively exploited?
CVE-2026-20066 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 61.6% of all scored CVEs.
What is the CVSS score of CVE-2026-20066?
CVE-2026-20066 has a CVSS v3 base score of 5.8 (NVD).
How do I remediate CVE-2026-20066?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-20066, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-20066
Is Your Infrastructure Affected by CVE-2026-20066?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.