Bypass of ZIA domain fronting detection module through evasion technique

published 2024-01-31 2 y ago modified 2026-06-17 4 mo ago also EUVD-2023-32442

cvss: 5.1; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 28%
public exploits: 0; none known

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.

Patch / fix

fixed in 1

Zscaler ZIA 6.2r.290

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 2 y ago (2024-03-14)

Exploit prediction

0.34% chance of exploitation in the next 30 days, higher than 28% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	5.1	CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
NVD	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Affected products

Zscaler ZIA

Classification

Weakness

CWE-295 Improper Certificate Validation

References

Sources

CVE List CVE-2023-28807
NVD CVE-2023-28807

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary