CVE-2026-102139: Kiteworks Email Protection Gateway Incorrect Authorization

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-30 · updated 2026-10-07
Weakness: CWE-639

Description

An authorization check in the large file exchange feature of Kiteworks Email Protection Gateway did not correctly establish that the requesting user was a party to the package being requested. An authenticated user of that optional feature could read the subject, message body, and attachments of packages they neither sent nor received.

Affected products

Kiteworks Email Protection Gateway: before 9.5.1 — fixed in 9.5.1

How to fix

Upgrade to a fixed version: Kiteworks Email Protection Gateway 9.5.1. Check the vendor advisory for mitigations.

References

https://github.com/kiteworks/security-advisories/security/advisories/GHSA-fp46-xhg8-vpgm
https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/VA/white/2026/va-26-274-01.json

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