PYSEC-2026-3000
Vulnerability from pysec - Published: 2026-07-13 15:46 - Updated: 2026-07-13 16:05
VLAI
Details
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.
Workarounds
Provide a correctly sized nb_blocks buffer.
pymonocypher thanks Haris (hextheshadow) for the vulnerability report, details, and recommended fix.
Severity
Impacted products
| Name | purl | pymonocypher | pkg:pypi/pymonocypher |
|---|
Aliases
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "pymonocypher",
"purl": "pkg:pypi/pymonocypher"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "4.0.2.8"
}
],
"type": "ECOSYSTEM"
}
],
"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"
]
}
],
"aliases": [
"CVE-2026-53720",
"GHSA-8f95-v3jq-cj86"
],
"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.",
"id": "PYSEC-2026-3000",
"modified": "2026-07-13T16:05:55.334297Z",
"published": "2026-07-13T15:46:30.235469Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/jetperch/pymonocypher/security/advisories/GHSA-8f95-v3jq-cj86"
},
{
"type": "WEB",
"url": "https://github.com/jetperch/pymonocypher/commit/90ff5b13b13b5673c372e188f482d8c172e6ab86"
},
{
"type": "PACKAGE",
"url": "https://github.com/jetperch/pymonocypher"
},
{
"type": "PACKAGE",
"url": "https://pypi.org/project/pymonocypher"
},
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-8f95-v3jq-cj86"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-53720"
}
],
"severity": [
{
"score": "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",
"type": "CVSS_V4"
}
],
"summary": "pymonocypher: Potential heap buffer overflow on nb_blocks in argon2i_32 when provided buffer is too small"
}
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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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