CVE-2026-61666

HIGHPre-NVD 8.98.9—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.9 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 73% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
8.9EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.9Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

websocket-driver is a WebSocket protocol handler with pluggable I/O. Prior to 0.8.2, WebSocket::Driver.server() passes a malformed Host header to URI.parse in lib/websocket/http/request.rb without catching URI::InvalidURIError, allowing a remote client to crash a TCP-backed WebSocket server when the application does not catch the error from parse(). This issue is fixed in version 0.8.2.

CVSS v3
8.9
EG Score
8.9(medium)
EG Risk
40(Track)
EG Risk 40/100SSVC: 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 computed
Severity89% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
27%
KEV
Not listed

Published

July 21, 2026

Last Modified

September 10, 2026

Advisory Details (2)

Auto-updated Aug 17, 2026
Patch available. Sources: github, github_commit.
github_commit

commit 7d6fd87759a2 (faye/websocket-driver-ruby)

Fix landed in faye/websocket-driver-ruby commit 7d6fd87759a2 — awaiting tagged release

https://github.com/faye/websocket-driver-ruby/commit/7d6fd87759a2fdc83590d3b49ffa661dc53fa128
github Patch Available

Denial of service via malformed Host header · Advisory · faye/websocket-driver-ruby · GitHub

Affected: version 0.8.2 by making the request parser catch

https://github.com/faye/websocket-driver-ruby/security/advisories/GHSA-2x63-gw47-w4mm

Vendor Advisories for CVE-2026-61666(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(4 across 4 ecosystems)
Debian:12(1)
PackageVulnerable rangeFixed inDependents
ruby-websocket-driver0.6.3-3, 0.8.0-1, 0.8.1-1, 0.8.2-1——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
ruby-websocket-driver0.6.3-3, 0.8.0-1, 0.8.1-1, 0.8.2-1——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
ruby-websocket-driver0.6.3-3, 0.8.0-1, 0.8.1-10.8.2-1—
RubyGems(1)
PackageVulnerable rangeFixed inDependents
websocket-driver0.1.0 ... 0.8.1 (33 versions)0.8.2—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 10× in last 7d / 41× 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.

  1. 2026-09-11 14:53 UTCEPSS rescore
  2. 2026-09-11 09:37 UTCEPSS rescore
  3. 2026-09-10 20:39 UTCEG score recompute
  4. 2026-09-09 11:28 UTCEG score recompute
  5. 2026-09-08 22:01 UTCEPSS rescore
  6. 2026-09-07 22:35 UTCEG score recompute
  7. 2026-09-07 16:01 UTCEPSS rescore
  8. 2026-09-06 13:47 UTCEPSS rescore
  9. 2026-09-05 19:51 UTCEG score recompute
  10. 2026-09-05 08:47 UTCEG score recompute
  11. 2026-09-04 05:07 UTCEPSS rescore
  12. 2026-09-02 14:12 UTCEPSS rescore
  13. 2026-09-02 00:57 UTCEG score recompute
  14. 2026-09-01 13:54 UTCEPSS rescore
  15. 2026-09-01 04:40 UTCEPSS rescore
  16. 2026-08-31 00:37 UTCEG score recompute
  17. 2026-08-30 19:17 UTCEPSS rescore
  18. 2026-08-30 02:15 UTCEG score recompute
  19. 2026-08-30 01:22 UTCEPSS rescore
  20. 2026-08-28 21:42 UTCEPSS rescore
  21. 2026-08-27 22:21 UTCEG score recompute
  22. 2026-08-27 14:25 UTCEPSS rescore
  23. 2026-08-26 23:00 UTCEG score recompute
  24. 2026-08-26 14:46 UTCEPSS rescore
  25. 2026-08-26 00:44 UTCEG score recompute
Show 20 more
  1. 2026-08-25 13:49 UTCEPSS rescore
  2. 2026-08-24 14:46 UTCEG score recompute
  3. 2026-08-23 04:05 UTCEG score recompute
  4. 2026-08-23 00:19 UTCEPSS rescore
  5. 2026-08-22 05:56 UTCEG score recompute
  6. 2026-08-21 23:49 UTCEPSS rescore
  7. 2026-08-21 07:48 UTCEG score recompute
  8. 2026-08-20 22:55 UTCEPSS rescore
  9. 2026-08-19 22:35 UTCEG score recompute
  10. 2026-08-19 17:04 UTCEPSS rescore
  11. 2026-08-18 19:31 UTCEG score recompute
  12. 2026-08-18 13:48 UTCEPSS rescore
  13. 2026-08-17 17:28 UTCEG score recompute
  14. 2026-08-17 17:11 UTCEG score recompute
  15. 2026-08-17 16:30 UTCEG score recompute▲ 8.90
  16. 2026-08-17 16:29 UTCMITRE cvelistV5CVSS v3 → 8.9 · CVSS v4 → 8.9
  17. 2026-07-31 21:17 UTCEG score recompute
  18. 2026-07-26 10:29 UTCEG score recompute
  19. 2026-07-23 03:21 UTCEG score recompute
  20. 2026-07-21 19:19 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-61666?
CVE-2026-61666 is a high vulnerability published on July 21, 2026. websocket-driver is a WebSocket protocol handler with pluggable I/O. Prior to 0.8.2, WebSocket::Driver.server() passes a malformed Host header to URI.parse in lib/websocket/http/request.rb without catching URI::InvalidURIError, allowing a remote client to crash a TCP-backed WebSocket server when…
When was CVE-2026-61666 disclosed?
CVE-2026-61666 was first published in the National Vulnerability Database on July 21, 2026, with the most recent update on September 10, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-61666 actively exploited?
CVE-2026-61666 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 73.2% of all scored CVEs.
What is the CVSS score of CVE-2026-61666?
CVE-2026-61666 has a CVSS v3 base score of 8.9 (NVD).
How do I remediate CVE-2026-61666?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-61666, 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

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-61666

Explore →

Is Your Infrastructure Affected by CVE-2026-61666?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs