CVE-2026-42786— WebSocket fragmented message reassembly unbounded in bandit

WebSocket fragmented message reassembly unbounded in bandit

Allocation of Resources Without Limits or Throttling vulnerability in mtrudel bandit allows unauthenticated remote denial of service via memory exhaustion. The fragment reassembly path in 'Elixir.Bandit.WebSocket.Connection':handle_frame/3 in lib/bandit/websocket/connection.ex appends every incoming Continuation{fin: false} frame's payload to a per-connection iolist with no cumulative size cap. The existing max_frame_size option only bounds individual frames; a peer that streams an unbounded number of continuation frames without ever setting fin=1 grows BEAM heap linearly until the OS or a supervisor kills the process. Because the accumulation happens before WebSock.handle_in/2 is called, the application has no opportunity to interpose a size check. Phoenix Channels and LiveView both run over WebSock on Bandit, so a stock Phoenix application exposes this surface as soon as it accepts socket connections. This issue affects bandit: from 0.5.0 before 1.11.0.

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不加限制或调节的资源分配

Bandit 安全漏洞

Bandit是Mat Trudel个人开发者的一款高性能HTTP与WebSocket服务器。 Bandit 0.5.0版本至1.11.0之前版本存在安全漏洞，该漏洞源于WebSocket连接中片段重组路径未对累积的续帧有效载荷设置大小上限，可能导致未经身份验证的远程拒绝服务。

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