Vibe Coding
MCP PHP SDK Buffers an Entire SSE Stream With No Upper Bound (CVE-2026-53965)
Published 2026-08-25 at 6.9, this hits the official Composer package `mcp/sdk` in versions 0.5.0 through 0.7.0. Its HTTP client transport reads a Server-Sent Events response incrementally, appends each chunk to an in-memory buffer with no cap, and only flushes on a double-newline event delimiter, so a remote MCP server that streams without ever sending a delimiter exhausts the client's memory. Same shape as PraisonAI's unbounded `_sessions` growth in CVE-2026-55531 filed the same day: MCP clients are trusting servers as much as servers trust clients.
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