PatchTheCVECVE-2021-32559: An integer overflow exists in pywin32 prior to version b301 when adding an access control entry (ACE) to an ac
CVE-2021-32559 is a medium-severity flaw (CVSS 6.5) affecting pywin32. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
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.
Why this priority
- No elevated risk signals yet
A fixed release or distro patch exists.
Risk facts
| CVSS score | 6.5 (Medium) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | Low |
| User interaction | None |
| EPSS exploit chance | 1.7% (top 22%) |
| CISA exploited list | No |
| Weakness | CWE-190 |
| Published | 2021-07-06 |
| Last modified | 2026-06-17 |
Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2021-32559?
pywin32: upgrade to 301. Exact commands for each OS are on this page.
Is CVE-2021-32559 being exploited?
CVE-2021-32559 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2021-32559 affect?
CVE-2021-32559 affects pywin32. Severity is medium (CVSS 6.5). 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 vuln
How urgent is CVE-2021-32559?
Priority 42/100. No elevated risk signals yet.