Http4s: WebSocket decoder accepts negative length, causing infinite decode loop
21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.5epss 0.5%
exploitation probability
0.5%top 60% of all CVEs
observed exploitation
nono source reports it
Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, WebSocket FrameTranscoder.bodyLength rejects extended payload lengths above Integer.MAX_VALUE but permits negative 64-bit lengths. A remote client that completes a WebSocket handshake through an Ember server can send such a frame, causing the decoder to return an empty frame without advancing its input. The decode loop then runs indefinitely, pins a worker at full CPU, and grows an ArrayBuffer without bound, resulting in denial of service. This issue is fixed in versions 0.23.35 and 1.0.0-M47.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Affected products
http4s · http4s