What’s Vulnerable › Vulnerabilities

CVE-2023-28807: Bypass of ZIA domain fronting detection module through evasion technique

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2024-01-31 · updated 2026-06-17
• Weakness: CWE-295

Description

In Zscaler Internet Access (ZIA) a mismatch between Connect Host and Client Hello's Server Name Indication (SNI) enables attackers to evade network security controls by hiding their communications within legitimate traffic.

Affected products

• Zscaler Secure Internet And Saas Access: before 6.2r.290 — fixed in 6.2r.290

How to fix

Upgrade to a fixed version: Zscaler Secure Internet And Saas Access 6.2r.290. Check the vendor advisory for mitigations.

References

• https://help.zscaler.com/zia/configuring-advanced-settings#dns-optimization
• https://help.zscaler.com/zia/configuring-advanced-settings#domain-fronting
• https://help.zscaler.com/zia/configuring-advanced-settings#dns-optimization
• https://help.zscaler.com/zia/configuring-advanced-settings#domain-fronting

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