Integer overflow in pywin32
An integer overflow exists in pywin32 prior to version b301 when adding an access control entry (ACE) to an access control list (ACL) that would cause the size to be greater than 65535 bytes. An attacker who successfully exploited this vulnerability could crash the vulnerable process.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | pywin32 | < 301 | 301 |
References
- https://github.com/mhammond/pywin32/releases
- https://github.com/fireeye/Vulnerability-Disclosures/blob/master/FEYE-2021-0017/FEYE-2021-0017.md
- https://github.com/advisories/GHSA-hwfp-hg2m-9vr2
- https://nvd.nist.gov/vuln/detail/CVE-2021-32559
- https://github.com/mhammond/pywin32/issues/1700
- https://github.com/mhammond/pywin32/pull/1701
- https://github.com/mhammond/pywin32
- https://github.com/pypa/advisory-database/tree/main/vulns/pywin32/PYSEC-2021-112.yaml
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H- Weakness (CWE)
CWE-190- Platform
- Python (PyPI)
- Package
pywin32- Disclosed
- 06.07.2021
- Updated
- 11.10.2026 12:19
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2021-112 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-hwfp-hg2m-9vr2 - CC BY 4.0
Vulnerability history: pywin32
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
This is the only known vulnerability of this package.
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