How severe is CVE-2020-11633?

CVE-2020-11633 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2020-11633 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (77th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-11633?

CVE-2020-11633 affects Zscaler Client Connector. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-11633?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2020-11633 published?

CVE-2020-11633 was published on 2021-07-15 and last updated on 2026-06-17.

CVE-2020-11633

CVE-2020-11633 is a critical-severity vulnerability in Zscaler Client Connector with a CVSS 3.x base score of 9.8. 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-787.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 10.0
EPSS exploit prediction: 2% (77th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-787
Affected product: Zscaler Client Connector
Published: 2021-07-15
Last modified: 2026-06-17

Description

The Zscaler Client Connector for Windows prior to 2.1.2.74 had a stack based buffer overflow when connecting to misconfigured TLS servers. An adversary would potentially have been able to execute arbitrary code with system privileges.

Frequently asked questions

What is CVE-2020-11633?: The Zscaler Client Connector for Windows prior to 2.1.2.74 had a stack based buffer overflow when connecting to misconfigured TLS servers. An adversary would potentially have been able to execute arbitrary code with system privileges.
How severe is CVE-2020-11633?: CVE-2020-11633 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2020-11633 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (77th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-11633?: CVE-2020-11633 affects Zscaler Client Connector. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-11633?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2020-11633 published?: CVE-2020-11633 was published on 2021-07-15 and last updated on 2026-06-17.

References

https://help.zscaler.com/zscaler-client-connector/client-connector-app-release-summary-2020?applicable_category=Windows&applicable_version=2.1.2.81

Affected products (1)

cpe:2.3:a:zscaler:client_connector:*:*:*:*:*:windows:*:*

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