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CVE-2026-61666 — Vulnerability in websocket-driver — CVE Details

HIGH

websocket-driver-ruby: Denial of service via malformed Host header

Published July 21, 2026Updated September 10, 2026Source: osv

Summary

### Impact If this library is used to implement a WebSocket server on top of a TCP server, by using the `WebSocket::Driver.server()` method, then a client can cause the server to crash by sending a `Host` header that is not a valid `host[:port]` string. When this happens, a `URI::InvalidURIError` exception is raised which is not caught, and this can cause the server process to crash if the application does not catch the error from the `parse()` method itself. ### Patches The issue has been patched in version 0.8.2 by making the request parser catch `URI::InvalidURIError` and enter an error state if the `Host` header is malformed. This means the request is considered invalid and should not establish a WebSocket connection. ### Workarounds No known workarounds exist. ### Acknowledgements This issue was discovered and reported by Pranjali Thakur, DepthFirst Security Research Team.

Advisory Timeline

  • First published July 21, 2026 (83 days ago).
  • Last revised September 10, 2026 — 50 days after initial publication.

Remediation

Upgrade to the fixed version using your package manager.

Bundler
Update websocket-driver to 0.8.2 or later
gem install websocket-driver -v 0.8.2

After upgrading, run your dependency scanner again to confirm the vulnerability is resolved.

Affected Packages (1)

Affects 1 ecosystem: rubygems (1).

PackageEcosystemAffectedFixed In
websocket-driver
rubygems
0.1.0, 0.2.0, 0.2.1, 0.2.2 (+29 more)0.8.2

Vulnerability Classification

Common Weakness Enumeration (CWE) identifiers for this vulnerability type.

CVSS Score Breakdown

What the CVSS (Common Vulnerability Scoring System) 8.0 score means for each attack dimension.

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
—
Confidentiality
—
Integrity
—
Availability
—

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H

Frequently Asked Questions

What is CVE-2026-61666?
websocket-driver-ruby: Denial of service via malformed Host header This vulnerability has been assigned a severity rating of HIGH (CVSS score: 8.0/10).
How do I check if my project is affected by CVE-2026-61666?
CVE-2026-61666 affects websocket-driver. Use GeekWala's free vulnerability scanner to check your dependencies against CVE-2026-61666 and 200,000+ other known vulnerabilities.

Severity & Exploitability

CVSS Score
8.0

High exploitability or significant impact. Prioritize remediation within days.

Also Known As

GHSA-2x63-gw47-w4mm

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