pymonocypher: Potential heap buffer overflow on nb_blocks in argon2i_32 when provided buffer is too small
Priority LOW 22CWE-122Published · Updated
Key facts
- Attack vector
- Local
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- —
- Confidentiality · integrity · availability
- None · Low · Low
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub.
Summary
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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00178 7th percentileScored 2026-11-07
Fix Fixed pymonocypher (jetperch): 4.0.2.8pymonocypher (PyPI): 4.0.2.8
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| jetperch | pymonocypher | before 4.0.2.8 | 4.0.2.8 | Patch available | CNA |
| — | pymonocypher (PyPI) | before 4.0.2.8 | 4.0.2.8 | Patch available | GHSA-8f95-v3jq-cj86 |
- pymonocypher Vendorjetperch Affected before 4.0.2.8 Fixed in 4.0.2.8 Patch available CNA
- pymonocypher (PyPI) Vendor— Affected before 4.0.2.8 Fixed in 4.0.2.8 Patch available GHSA-8f95-v3jq-cj86
Remediation
- Fix · CNA pymonocypher (jetperch) Fixed in 4.0.2.8
- Fix · GHSA-8f95-v3jq-cj86 pymonocypher (PyPI) Fixed in 4.0.2.8 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-53720
- 2026-10-03 Alias added: GHSA-8f95-v3jq-cj86
References
Sources
- CVE-2026-53720 · CVE Program
- CVE-2026-53720 · NVD
- FIRST EPSS
- GHSA-8f95-v3jq-cj86 · GitHub Advisory Database · CC BY 4.0
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