CVE-2021-32559

Name: CVE-2021-32559
Creator: NVD / NIST
Published: 2021-07-06T12:15:21.887+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 1.73%

Last modified Jun 17, 2026

CVE-2021-32559 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. 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.. EPSS estimates a 1.73% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

6.5/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

1.73%

74.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-190

Affected Software

Vendor	Product	Versions
Mhammond	Pywin32	< 301

References

https://github.com/fireeye/Vulnerability-Disclosures/blob/master/FEYE-2021-0017/FEYE-2021-0017.mdThird Party Advisory
https://github.com/mhammond/pywin32/issues/1700Patch, Third Party Advisory
https://github.com/mhammond/pywin32/pull/1701Third Party Advisory
https://github.com/mhammond/pywin32/releasesRelease Notes, Third Party Advisory
https://github.com/fireeye/Vulnerability-Disclosures/blob/master/FEYE-2021-0017/FEYE-2021-0017.mdThird Party Advisory
https://github.com/mhammond/pywin32/issues/1700Patch, Third Party Advisory
https://github.com/mhammond/pywin32/pull/1701Third Party Advisory
https://github.com/mhammond/pywin32/releasesRelease Notes, Third Party Advisory

Timeline

Published: Jul 6, 2021
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2021-32559?

How severe is CVE-2021-32559?

CVE-2021-32559 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 1.73% probability of exploitation in the next 30 days.

How do I fix CVE-2021-32559?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-32559?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST