Kiteworks Email Protection Gateway: Improper access control allows certificate misassignment
Summary
Kiteworks Email Protection Gateway (EPG) versions before 9.5.1 do not sufficiently restrict which account a certificate can be assigned to. An attacker can associate a certificate with another user's account, which may expose that account's encrypted mail and, where certificate-based login is enabled, allow unauthorized access to the account. CVSS 9.4 (Critical); the CVE record and vendor text do not clearly state whether authentication is required, and the exact prerequisites remain to be confirmed.
Affected
- Kiteworks Email Protection Gateway versions before 9.5.1
- Affected per CVE record: 0 to < 9.5.1
Fixed in
- Upgrade to Kiteworks Email Protection Gateway 9.5.1 or later
Workaround
- Unknown. No vendor-published workaround was identified.
- Restrict access to the EPG management interface to administrators and trusted networks until the upgrade is complete.
Exploitation
- CISA SSVC: exploitation none, automatable yes, technical impact total.
- No reports of exploitation in the wild and no public proof of concept were found in the research.
- Not listed in the CISA KEV catalog.
Our recommendation
- Confirm the EPG version on all instances and upgrade to 9.5.1 or later.
- Check whether certificate-based login is enabled; if not, the login-related impact is lower.
- Review audit logs for certificate assignments where the certificate does not match the target account or the changing user differs from the receiving account.
- Restrict management interface access to administrators and trusted networks.
- Verify the fixed version and authentication requirements in GHSA-c9w5-4frw-7wqq before closing the ticket.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- GitHub Security Advisory GHSA-c9w5-4frw-7wqq github.com
- CISA CSAF va-26-274-01 raw.githubusercontent.com
- Canadian Centre for Cyber Security AV26-988 www.cyber.gc.ca
- TheHackerWire analysis www.thehackerwire.com
- VulDB CVE-2026-102149 vuldb.com
- OpenCVE CVE-2026-102149 app.opencve.io
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 31 Oct 2026, 00:21.
Original description (NVD)
Kiteworks Email Protection Gateway did not sufficiently restrict which account a certificate could be assigned to. This could allow an attacker to associate a certificate with another user's account, affecting the confidentiality and integrity of that account's encrypted mail and, where certificate-based login is enabled, potentially permitting unauthorized access to the account.
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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