CVE-2026-18717

Improper Certificate Validation in ASE 2000

Published Aug 27, 2026 CVSS 4.0 · 9.1 Critical EPSS < 1% KEV · Not listed
Description
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.

Remediation

Vendor Solution

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.


Vendor Workaround

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.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Applied Systems Engineering
Applied Systems Engineering ase2000 V2
Vendors & Products Applied Systems Engineering
Applied Systems Engineering ase2000 V2
Type Values Removed Values Added
Description 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.
Title Improper Certificate Validation in ASE 2000
Weaknesses CWE-295
References
Metrics cvssV3_1

{'score': 7.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N'}

cvssV4_0

{'score': 9.1, '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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
icscert
Published
Updated
Aug 28, 2026, 3:58 PM
Reserved
Aug 3, 2026, 4:30 PM
Status
Deferred
Published
Aug 28, 2026, 12:16 AM
Modified
Aug 31, 2026, 7:18 PM