Executive brief
ChangeDetection.io, a tool used to monitor websites for content changes, contains a security flaw that allows users to read sensitive files from the server's local storage. By using specific commands in the website's filtering settings, an attacker could access private configuration files or system data. This could lead to the exposure of credentials or other confidential information stored on the host machine.
Technical details
A protection bypass vulnerability exists in the SafeXPath3Parser implementation of ChangeDetection.io. The application uses a blocklist to prevent the execution of dangerous XPath functions; however, this list was incomplete, failing to include several XPath 3.0/3.1 file-access primitives. An authenticated attacker with network access can provide crafted XPath selectors using functions such as json-doc(), collection(), or uri-collection() to bypass security restrictions and read arbitrary files from the local filesystem. The issue is addressed in version 0.54.7 by expanding the blocklist in html_tools.py to include these functions.
Affected products
- dgtlmoon ChangeDetection.io < 0.54.7
Timeline
- 2026-03-26: patched: Version 0.54.7 released with fix
- 2026-04-01: disclosed: Initial vulnerability disclosure