BREW-mailcatcher-CVE-2026-54463 — websocket-driver: Memory exhaustion via abuse of protocol length headers

Affected: Homebrew: mailcatcher

### Impact

The frame format in draft versions of the WebSocket protocol includes a length header that allows an arbitrarily large integer to be encoded as a sequence of bytes with the high bit set. By sending an indefinite sequence of bytes with values `0x80` or above, a server or client can make the other peer parse these bytes into an ever-growing integer. Since Ruby integers are arbitrary precision, this can be used to make a WebSocket connection consume an unbounded amount of memory and lead to the host process running out of memory.

### Patches

The issue has been patched in version 0.8.1. 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.

CVE-2026-54463 — websocket-driver: Memory exhaustion via abuse of protocol length headers

Affected: faye websocket-driver-ruby

websocket-driver is a WebSocket protocol handler with pluggable I/O. Prior to 0.8.1, draft versions of the WebSocket protocol in websocket-driver include a length header that allows an arbitrarily large integer to be encoded as bytes with the high bit set, and a server or client can send an indefinite sequence of 0x80 or higher bytes that the peer parses into an ever-growing Ruby integer. This can make a WebSocket connection consume an unbounded amount of memory and lead to the host process running out of memory. This issue is fixed in version 0.8.1.

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BREW-mailcatcher-CVE-2026-54463 — websocket-driver: Memory exhaustion via abuse of protocol length headers

CVE-2026-54463 — websocket-driver: Memory exhaustion via abuse of protocol length headers