{"id":"CVE-2026-53720","aliases":["EUVD-2026-70531","GHSA-8f95-v3jq-cj86","PYSEC-2026-3000"],"status":"published","title":"pymonocypher: Potential heap buffer overflow on nb_blocks in argon2i_32 when provided buffer is too small","description":"pymonocypher uses cython to wrap the Monocypher C library. Prior to version 4.0.2.8, 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. This issue has been patched in version 4.0.2.8.","severity":{"version":"4.0","score":5.1,"vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00178,"percentile":0.07462,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-122","CWE-1284","CWE-787"],"published":"2026-07-09T13:42:46Z","modified":"2026-10-28T02:30:27Z","fixes":[{"ecosystem":"PyPI","package":"pymonocypher","fixed_in":["4.0.2.8"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"PyPI","package":"pymonocypher","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.0.2.8"}]}]},{"source":"osv","ecosystem":"PyPI","package":"pymonocypher","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.0.2.8"}]}],"versions":["0.1.1","0.1.2","0.1.3","0.1.4","3.1.0.0","3.1.3.0","3.1.3.1","3.1.3.2","3.1.3.3","3.1.3.4","3.1.3.5","3.1.3.6","4.0.2.1","4.0.2.2","4.0.2.3","4.0.2.4","4.0.2.5","4.0.2.6","4.0.2.7"]},{"source":"osv","ecosystem":"PyPI","package":"pymonocypher","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.0.2.8"}]}],"versions":["0.1.1","0.1.2","0.1.3","0.1.4","3.1.0.0","3.1.3.0","3.1.3.1","3.1.3.2","3.1.3.3","3.1.3.4","3.1.3.5","3.1.3.6","4.0.2.1","4.0.2.2","4.0.2.3","4.0.2.4","4.0.2.5","4.0.2.6","4.0.2.7"]}],"products":[{"vendor":"jetperch","product":"pymonocypher"}],"references":[{"url":"https://github.com/jetperch/pymonocypher/security/advisories/GHSA-8f95-v3jq-cj86","tags":["x_refsource_CONFIRM","advisory","web"]},{"url":"https://github.com/jetperch/pymonocypher/commit/90ff5b13b13b5673c372e188f482d8c172e6ab86","tags":["x_refsource_MISC","fix","web"]},{"url":"https://github.com/jetperch/pymonocypher/releases/tag/v4.0.2.8","tags":["x_refsource_MISC","web"]},{"url":"https://github.com/advisories/GHSA-8f95-v3jq-cj86","tags":["advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53720.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-53720","tags":["advisory"]},{"url":"https://github.com/jetperch/pymonocypher","tags":["package"]},{"url":"https://pypi.org/project/pymonocypher","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-53720","title":"pymonocypher: Potential heap buffer overflow on nb_blocks in argon2i_32 when provided buffer is too small","description":"pymonocypher uses cython to wrap the Monocypher C library. Prior to version 4.0.2.8, 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. This issue has been patched in version 4.0.2.8.","status":"published","published":"2026-09-03T15:30:06.69Z","modified":"2026-09-03T15:42:53.741Z","cvss":[{"version":"4.0","score":5.1,"vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N","level":"medium","assessor":"cna"}],"cwes":["CWE-122","CWE-787","CWE-1284"],"updated_at":"2026-11-02T14:19:59.761005Z"}],"euvd":[{"id":"EUVD-2026-70531","description":"pymonocypher uses cython to wrap the Monocypher C library. Prior to version 4.0.2.8, 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. This issue has been patched in version 4.0.2.8.","status":"published","published":"2026-09-03T15:30:06Z","modified":"2026-09-03T15:42:53Z","cvss":[{"version":"4.0","score":5.1,"vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N","level":"medium"}],"updated_at":"2026-11-02T18:01:13.671159Z"}],"ghsa":[{"id":"GHSA-8f95-v3jq-cj86","title":"pymonocypher: Potential heap buffer overflow on nb_blocks in argon2i_32 when provided buffer is too small","description":"### 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.","status":"published","published":"2026-07-09T13:42:46Z","modified":"2026-07-09T13:42:47Z","cvss":[{"version":"4.0","score":5.1,"vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N","level":"medium"}],"cwes":["CWE-122","CWE-787","CWE-1284"],"updated_at":"2026-11-02T14:40:41.501474Z"}],"nvd":[{"id":"CVE-2026-53720","description":"pymonocypher uses cython to wrap the Monocypher C library. Prior to version 4.0.2.8, 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. This issue has been patched in version 4.0.2.8.","status":"published","published":"2026-09-03T16:17:25.36Z","modified":"2026-09-09T21:09:13.08Z","cvss":[{"version":"4.0","score":5.1,"vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"medium","assessor":"secondary"}],"cwes":["CWE-122","CWE-787","CWE-1284"],"updated_at":"2026-11-02T14:12:43.399612Z"}],"osv":[{"id":"CVE-2026-53720","title":"pymonocypher: Potential heap buffer overflow on nb_blocks in argon2i_32 when provided buffer is too small","description":"pymonocypher uses cython to wrap the Monocypher C library. Prior to version 4.0.2.8, 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. This issue has been patched in version 4.0.2.8.","status":"published","published":"2026-09-03T15:30:06.69Z","modified":"2026-10-28T02:30:27.395908414Z","cvss":[{"version":"4.0","score":5.1,"vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N","level":"medium"}],"cwes":["CWE-122","CWE-1284","CWE-787"],"updated_at":"2026-11-02T15:45:08.132336Z"},{"id":"GHSA-8f95-v3jq-cj86","title":"pymonocypher: Potential heap buffer overflow on nb_blocks in argon2i_32 when provided buffer is too small","description":"### 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.","status":"published","published":"2026-07-09T13:42:46Z","modified":"2026-07-13T16:42:57.702687797Z","cvss":[{"version":"4.0","score":5.1,"vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N","level":"medium"}],"cwes":["CWE-122","CWE-1284","CWE-787"],"updated_at":"2026-11-02T15:46:42.077781Z"},{"id":"PYSEC-2026-3000","title":"pymonocypher: Potential heap buffer overflow on nb_blocks in argon2i_32 when provided buffer is too small","description":"### 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.","status":"published","published":"2026-07-13T15:46:30.235469Z","modified":"2026-07-13T16:33:07.802709798Z","cvss":[{"version":"4.0","score":5.1,"vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N","level":"medium"}],"updated_at":"2026-11-02T15:52:56.429374Z"}]}}