The vulnerability in HSC MailInspector 5.3.3-7 involves insufficient validation of the 'text' parameter in the /tap/dw.php endpoint, enabling path traversal attacks. Because the application constructs file paths directly from user input without enforcing a safe base directory or normalizing paths, an attacker can manipulate the input to access files outside the intended directory scope. This can lead to unauthorized disclosure of sensitive files on the server's filesystem. The vulnerability is publicly documented as CVE-2026-29963 but lacks a CVSS score and official remediation guidance.

Successful exploitation permits remote attackers to read arbitrary files on the server hosting HSC MailInspector, leading to unauthorized disclosure of potentially sensitive information. This could compromise confidentiality depending on the files accessed. No information is available about further impacts such as code execution or service disruption.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, restrict access to the vulnerable endpoint and consider implementing web application firewall rules to detect and block path traversal patterns targeting the /tap/dw.php endpoint. Avoid exposing this service to untrusted networks where possible.