CVE-2026-61666
websocket-driver-ruby: Denial of service via malformed Host header
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.
Affected packages
| Ecosystem | Package | Affected versions | Fixed versions |
|---|---|---|---|
| RubyGems | websocket-driver | — | 0.8.2 |
Remediation: Upgrade to 0.8.2 or later.
References
Includes data from the GitHub Advisory Database, licensed under CC-BY 4.0.
CVE® is a registered trademark of The MITRE Corporation. CVE content reproduced under the CVE Terms of Use; copyright designation © MITRE.