pymonocypher uses cython to wrap the Monocypher C library. Prior to version 4.0.2.8, the argon2i32 implementation does not check the nbblocks 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. This issue has been patched in version 4.0.2.8.
{
"cwe_ids": [
"CWE-122",
"CWE-1284",
"CWE-787"
],
"cna_assigner": "GitHub_M",
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53720.json"
}