CVE-2026-54464: websocket-driver: Resource limit bypass via message compression

Severity: medium (CVSS 6.3 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-17 · updated 2026-10-24
Weakness: CWE-770

Description

### Impact If this library is used in tandem with the `permessage-deflate` extension, a WebSocket server or client can be made to accept messages that are larger than the configured maximum message size. This is because this limit is checked against the message frames' length headers, which give the size of the compressed data, not the size after decompression. This can lead to applications accepting larger messages than expected and exceeding their intended resource usage. ### Patches The issue has been patched in version 0.8.1, by checking the length of messages after they are processed by incoming extensions. All users should upgrade to this version. ### Workarounds No known workarounds exist. ### Acknowledgements This issue was discovered and reported by Pranjali Thakur, DepthFirst Security Research Team.

Affected products

Rubygems Websocket-Driver: before 0.8.1; 0.1.0, 0.2.0, 0.2.1, 0.2.2, 0.2.3, 0.3.0 (+26) — fixed in 0.8.1
faye websocket-driver-ruby: before 0.8.1

How to fix

Upgrade to a fixed version: Rubygems Websocket-Driver 0.8.1. Check the vendor advisory for mitigations.

References

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