Advisories for Pypi/Autobahn package

2026

Autobahn Python: permessage-brotli inflates a whole frame before maxMessagePayloadSize is checked (incomplete fix of GHSA-hxp9-w8x3-p566)

permessage-brotli inflates each frame fully before checking maxMessagePayloadSize, so one 421-byte frame makes the server allocate about 545 MiB even with a 1 MiB message limit (brotli expands about 1,000,000:1). Any unauthenticated client can exhaust server memory this way on servers that enable permessage-brotli. This bypasses the GHSA-hxp9-w8x3-p566 fix.

Autobahn Python permessage-deflate bypasses maxMessagePayloadSize after inflation

Autobahn Python enforces maxMessagePayloadSize against the compressed WebSocket frame length before permessage-deflate inflation, then delivers the inflated message to application callbacks without a second size check. A client frame that is only 22 compressed bytes can inflate to 4096 bytes and reach onMessage even when the application configured a 128-byte message limit, defeating the resource boundary the option is meant to provide.

2020