Impact The argon2i_32 implementation does not check the nb_blocks size. If the caller does not provide a sufficiently large buffer based on the API contract, then argon2i_32 will write past the end of the buffer and possibly corrupt the heap. Patches Fixed in 4.0.2.8, which now verifies that nb_blocks is large enough. See "90ff5b1" (https://github.com/jetperch/pymonocypher/commit/90ff5b13b13b5673c372e188f482d8c172e6ab86). Workarounds Provide a correctly sized nb_blocks buffer. pymonocypher thanks Haris (hextheshadow) for the vulnerability report, details, and recommended fix.