CVE-2026-41895

changedetection.io_XXE_01 Vulnerability Report: We discovered a XXE vulnerability in the changedetection.io project

While analyzing the code logic, it was determined that an area may lead to unintended behavior under specific conditions. With the project's security in mind, see the analysis results to discern whether this may indicate a potential security risk.

Overview

• SOURCE_VERSION: 0.54.9 (9f3a9fdc18bba404244801e5df8109e213ce9ff4)
• Vulnerability type: XXE
• Finding title: XML XPath helpers parse untrusted XML with entity resolution left to lxml defaults
• Affected location: changedetectionio/html_tools.py:287

Root Cause

xpath_filter() switches to XML mode for XML/RSS content and creates etree.XMLParser(strip_cdata=False) without explicitly disabling external entity resolution, external DTD loading, or network-backed entity lookup. The helper then parses untrusted XML bytes directly with etree.fromstring(...).

Source-to-Sink Chain

1. Untrusted XML/RSS response content is fetched from monitored URLs.
2. Stream detection marks the content as XML/RSS and the include-filter path invokes xpath_filter(..., is_xml=True).
3. xpath_filter() builds the default XML parser and calls etree.fromstring(...) at changedetectionio/html_tools.py:287.
4. External entity declarations in attacker XML can be expanded by parser-default behavior in affected runtime combinations.

Exploitation Preconditions

1. Attacker controls the watched XML/RSS response body.
2. The watch uses an XPath include filter that triggers XML helper parsing.
3. Runtime parser behavior allows external entity expansion (for example, vulnerable dependency/default combinations).
4. The process can read the referenced local resource.

Risk

The XML helper path can turn watch processing into a local file disclosure primitive when entity expansion is enabled by parser defaults.

Sensitive local files can be exposed into extracted watch output, diff history, and downstream notification channels.

An XML parser processes external entity references in untrusted input, causing the server to fetch internal resources or remote URLs. Typical impact: local file disclosure, server-side request forgery, or denial of service.

CVE-2026-41895 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.

Kodem intelligence

1. Harden XML parser construction with resolve_entities=False, load_dtd=False, and no_network=True.
2. Reject DOCTYPE/entity declarations for untrusted XML if DTD features are unnecessary.
3. Add regression tests that assert external entities are never expanded in XPath XML helper flows.

1. What is CVE-2026-41895? CVE-2026-41895 is a high-severity XML external entity injection (XXE) vulnerability in changedetection.io (pip), affecting versions <= 0.54.9. No fixed version is listed yet. An XML parser processes external entity references in untrusted input, causing the server to fetch internal resources or remote URLs.
2. How severe is CVE-2026-41895? CVE-2026-41895 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of changedetection.io are affected by CVE-2026-41895? changedetection.io (pip) versions <= 0.54.9 is affected.
4. Is there a fix for CVE-2026-41895? No fixed version is listed for CVE-2026-41895 yet. Monitor the advisory for updates and apply mitigations in the interim.
5. Is CVE-2026-41895 exploitable, and should I be worried? Whether CVE-2026-41895 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-41895 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-41895? No fixed version is listed yet. In the interim: Disable external entity and DTD processing in your XML parser configuration.