How severe is CVE-2021-32559?

CVE-2021-32559 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-32559 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (75th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-32559?

CVE-2021-32559 affects Mhammond Pywin32. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-32559?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-32559 published?

CVE-2021-32559 was published on 2021-07-06 and last updated on 2026-06-17.

CVE-2021-32559

CVE-2021-32559 is a medium-severity vulnerability in Mhammond Pywin32 with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-190.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 4.0
EPSS exploit prediction: 2% (75th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-190
Affected product: Mhammond Pywin32
Published: 2021-07-06
Last modified: 2026-06-17

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.

Frequently asked questions

What is 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 would cause the size to be greater than 65535 bytes. An attacker who successfully exploited this vulnerability could crash the vulnerable process.
How severe is CVE-2021-32559?: CVE-2021-32559 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-32559 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (75th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-32559?: CVE-2021-32559 affects Mhammond Pywin32. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-32559?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-32559 published?: CVE-2021-32559 was published on 2021-07-06 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:mhammond:pywin32:*:*:*:*:*:*:*:*

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