{"id":"CVE-2026-53720","aliases":["GHSA-8f95-v3jq-cj86","PYSEC-2026-3000"],"url":"https://o3.security/vulnerability/CVE-2026-53720","summary":"pymonocypher: Potential heap buffer overflow on nb_blocks in argon2i_32 when provided buffer is too small","details":"### Impact\nThe 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.\n\n### Patches\nFixed in 4.0.2.8, which now verifies that nb_blocks is large enough.  See [90ff5b1](https://github.com/jetperch/pymonocypher/commit/90ff5b13b13b5673c372e188f482d8c172e6ab86).\n\n### Workarounds\nProvide a correctly sized nb_blocks buffer.\n\npymonocypher thanks Haris (hextheshadow) for the vulnerability report, details, and recommended fix.","published":"2026-09-03T15:30:06.690Z","modified":"2026-10-21T02:58:30.370909605Z","cvss":null,"epss":{"score":0.00126,"percentile":0.02602,"asOf":"2026-09-17"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"pymonocypher","fixedVersion":"4.0.2.8"}],"fix":{"url":"https://github.com/jetperch/pymonocypher/commit/90ff5b13b13b5673c372e188f482d8c172e6ab86","label":"jetperch/pymonocypher@90ff5b1"},"references":[{"type":"WEB","url":"https://github.com/jetperch/pymonocypher/releases/tag/v4.0.2.8"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53720.json"},{"type":"ADVISORY","url":"https://github.com/jetperch/pymonocypher/security/advisories/GHSA-8f95-v3jq-cj86"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-53720"},{"type":"FIX","url":"https://github.com/jetperch/pymonocypher/commit/90ff5b13b13b5673c372e188f482d8c172e6ab86"},{"type":"PACKAGE","url":"https://github.com/jetperch/pymonocypher"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-21T02:58:30.370909605Z"}}