CVE-2026-18717 PUBLISHED

Improper Certificate Validation in ASE 2000

Assigner: icscert
Reserved: 03.08.2026 Published: 27.08.2026 Updated: 27.08.2026

ASE2000 2.35 through 2.37 is vulnerable to an improper certificate validation vulnerability, which may allow an attacker to impersonate the trusted peer, complete the TLS handshake, and read or modify protected communications.

Metrics

CVSS Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
CVSS Score: 9.1

Product Status

Vendor Applied Systems Engineering
Product ASE2000 V2
Versions Default: unaffected
  • affected from 2.25 to 2.37 (incl.)
  • Version 2.38 is unaffected

Workarounds

Until the upgrade can be applied, the following interim measures reduce exposure:

  • Restrict write access to the ASE2000 installation directory and its configuration files to trusted administrators only.
  • Avoid using IEC 60870-5-104 over TLS across untrusted or shared networks; place ASE2000 hosts on an isolated, segmented network reachable only by intended peers.
  • Ensure the host is protected by a network firewall.

Solutions

ASE/Kalkitech provides an upgraded version 2.38 that fixes both vulnerabilities and customers are advised to upgrade to version 2.38. In version 2.38 the bundled log4net library is upgraded to version 3.3.1.0, and the IEC 60870-5-104 TLS client certificate validation logic is corrected to ensure proper validation of certificate error conditions.

All customers running ASE2000 versions 2.25 through 2.37 are affected by this issue and are required to upgrade to version 2.38 or later to apply the security fix. Upgrade instructions and user documentation are available at www.ase-systems.com . For detailed, step-by-step guidance on upgrading to the latest version and patching the impacted components, please contact our support team at support@ase-systems.com.

Credits

  • Enoch Wang reported this vulnerability to CISA. finder

References

Problem Types

  • CWE-295 Improper certificate validation CWE