Advisories for Cargo/Pageant package

pageant::PageantStream reads a 4-byte big-endian length prefix from its input stream and buffers until len + 4 bytes are available, without ever validating len. The underlying WM_COPYDATA transport physically cannot carry frames larger than 8 KiB (_AGENT_MAX_MSGLEN, the fixed-size shared memory mapping), so an oversized frame is destined to fail — but only after the re-framing task has already buffered the full claimed size. A peer controlling the stream bytes …

MemoryMap::read in the pageant crate (part of the russh workspace, used by russh's SSH-agent client on Windows via AgentClient::connect_pageant) copies a peer-controlled number of bytes out of an 8192-byte shared-memory view with no bounds check — unlike the sibling MemoryMap::write, which correctly rejects oversize access with Error::Overflow. The byte count comes straight from a u32 length prefix that the responding "Pageant" process writes into the shared mapping. A malicious local …