How severe is CVE-2021-26737?

CVE-2021-26737 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-26737 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (1st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-26737?

CVE-2021-26737 affects Zscaler Client Connector. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-26737?

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

When was CVE-2021-26737 published?

CVE-2021-26737 was published on 2023-10-23 and last updated on 2026-06-17.

CVE-2021-26737

CVE-2021-26737 is a medium-severity vulnerability in Zscaler Client Connector with a CVSS 3.x base score of 5.5. 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-346.

Key facts

Severity: Medium (CVSS 3.x base score 5.5)
EPSS exploit prediction: 0% (1st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-346
Affected product: Zscaler Client Connector
Published: 2023-10-23
Last modified: 2026-06-17

Description

The Zscaler Client Connector for macOS prior to 3.6 did not sufficiently validate RPC clients. A local adversary without sufficient privileges may be able to shutdown the Zscaler tunnel by exploiting a race condition.

Frequently asked questions

What is CVE-2021-26737?: The Zscaler Client Connector for macOS prior to 3.6 did not sufficiently validate RPC clients. A local adversary without sufficient privileges may be able to shutdown the Zscaler tunnel by exploiting a race condition.
How severe is CVE-2021-26737?: CVE-2021-26737 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-26737 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (1st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-26737?: CVE-2021-26737 affects Zscaler Client Connector. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-26737?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-26737 published?: CVE-2021-26737 was published on 2023-10-23 and last updated on 2026-06-17.

References

https://help.zscaler.com/client-connector/client-connector-app-release-summary-2022?applicable_category=macOS&applicable_version=3.6&deployment_date=2022-01-07&id=1388686

Affected products (1)

cpe:2.3:a:zscaler:client_connector:*:*:*:*:*:macos:*:*

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