CVE-2019-25589: 
Homebrew vulnerability analysis and mitigation

CVE-2019-25589 is a buffer overflow (out-of-bounds write) vulnerability in ZOC Terminal version 7.23.4, developed by EmTec. The flaw resides in the Shell field of the application's Program Settings, allowing a local attacker to crash the application by entering an excessively long string. The vulnerability was formally published on March 22, 2026, and carries a CVSS v3.1 base score of 5.5 (Medium) and a CVSS v4.0 base score of 6.9 (Medium) (VulnCheck Advisory, Exploit-DB).

The root cause is an out-of-bounds write (CWE-787) caused by insufficient bounds checking on user-supplied input in the Shell configuration field within ZOC Terminal's Program Settings. An attacker with local access can paste a crafted, excessively long string into this field; when the application subsequently accesses the Command Shell feature, the oversized input overflows an internal buffer, causing the application to crash. Exploitation requires only low privileges and no user interaction beyond the initial configuration change. A proof-of-concept entry exists on Exploit-DB (EDB-46857) (Exploit-DB, VulnCheck Advisory).

Successful exploitation results in a denial-of-service condition — specifically, a crash of the ZOC Terminal application — affecting availability with no impact on confidentiality or integrity. The scope is limited to the local system and the affected application instance, with no evidence of lateral movement potential or data exposure risk. The impact is confined to users relying on ZOC Terminal's Command Shell feature for terminal emulation or SSH/Telnet sessions (VulnCheck Advisory).

A proof-of-concept entry is listed on Exploit-DB (EDB-46857), though Feedly's analysis classifies it as non-exploitable based on available metadata, and there is no confirmed evidence of in-the-wild exploitation. The EPSS score is approximately 0.012% (0.000120), indicating a very low probability of exploitation in the near term. The vulnerability is not listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, and no threat actor attribution has been reported (Exploit-DB, VulnCheck Advisory).

1. Access Program Settings: Obtain local access to a system running ZOC Terminal 7.23.4 and open the application's Program Settings dialog.
2. Locate the Shell field: Navigate to the section containing the Shell configuration field within Program Settings.
3. Inject oversized payload: Paste a crafted, excessively long string (e.g., a string of several hundred or more repeated characters) into the Shell field and save the settings.
4. Trigger the crash: Attempt to access the Command Shell feature within ZOC Terminal; the application will process the malformed Shell field value, trigger a buffer overflow, and crash (Exploit-DB).

• Logs: Unexpected application crash logs or Windows Event Log entries (Event ID 1000/1001) referencing the ZOC Terminal process (zoc.exe) with a faulting module indicating a memory access violation.
• File System: Unusual or modified ZOC Terminal configuration files (e.g., zoc.ini or equivalent settings files) containing abnormally long strings in the Shell field.
• Process: Abrupt termination of the zoc.exe process without user-initiated exit, particularly when the Command Shell feature is accessed.

No official vendor patch has been confirmed as available for CVE-2019-25589 at the time of publication. As interim mitigations, administrators should restrict access to ZOC Terminal's Program Settings to trusted users only, monitor for suspicious or unauthorized configuration changes, and consider disabling the Command Shell feature if it is not operationally required. Users should monitor the EmTec website for updated releases and apply any available patches promptly (VulnCheck Advisory, EmTec).