GHSA-9JJ8-V89V-XJVW

Vulnerability from github – Published: 2026-07-20 19:06 – Updated: 2026-07-20 19:06
VLAI
Summary
changedetection.io is vulnerable to unauthenticated static path traversal
Details

Summary

The /static/<group>/<filename> route accepts group="..", which causes send_from_directory("static/..", filename) to execute. This moves the base directory up to /app/changedetectionio, enabling unauthenticated local file read of application source files (e.g., flask_app.py). Severity is low information disclosure (C:L).

Details

The vulnerable code is in changedetectionio/flask_app.py inside static_content():

group = re.sub(r'[^\w.-]+', '', group.lower())
filename = re.sub(r'[^\w.-]+', '', filename.lower())
...
return send_from_directory(f"static/{group}", path=filename)

The group sanitization allows dots, so group=".." passes validation.
This results in send_from_directory("static/..", filename), effectively shifting the base directory to /app/changedetectionio and allowing reads of files in that directory.
The route is unauthenticated, so any user can retrieve source files without logging in.

Limitation: the route only matches /static/<group>/<filename> and rejects slashes inside filename, so it cannot traverse further to arbitrary system paths like /etc/passwd. It is limited to files inside the application package directory.

PoC

1) Start an instance (example: Docker on port 5050)

docker run -d --name cdio -p 127.0.0.1:5050:5000 -v cdio-data:/datastore cdio-local

2) Reproduce
(URL-encoded traversal)

curl -i http://127.0.0.1:5050/static/%2e%2e/flask_app.py

(curl path passthrough)

curl --path-as-is -i http://127.0.0.1:5050/static/../flask_app.py

3) Observe that the response body contains Python source code from flask_app.py.

Impact

  • Vulnerability type: Directory Traversal / Local File Read
  • Affected users: Anyone with network access (no authentication required)
  • Scope: Source files under /app/changedetectionio
  • Security impact: Internal logic exposure can aid further exploitation (Confidentiality: Low)
Severity
5.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "changedetection.io"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.53.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-25527"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-20T19:06:55Z",
    "nvd_published_at": "2026-02-19T15:16:11Z",
    "severity": "MODERATE"
  },
  "details": "## Summary\nThe `/static/\u003cgroup\u003e/\u003cfilename\u003e` route accepts `group=\"..\"`, which causes `send_from_directory(\"static/..\", filename)` to execute. This moves the base directory up to `/app/changedetectionio`, enabling **unauthenticated local file read** of application source files (e.g., `flask_app.py`). Severity is **low information disclosure (C:L)**.\n\n### Details\nThe vulnerable code is in `changedetectionio/flask_app.py` inside `static_content()`:\n\n```\ngroup = re.sub(r\u0027[^\\w.-]+\u0027, \u0027\u0027, group.lower())\nfilename = re.sub(r\u0027[^\\w.-]+\u0027, \u0027\u0027, filename.lower())\n...\nreturn send_from_directory(f\"static/{group}\", path=filename)\n```\n\nThe `group` sanitization allows dots, so `group=\"..\"` passes validation.  \nThis results in `send_from_directory(\"static/..\", filename)`, effectively shifting the base directory to `/app/changedetectionio` and allowing reads of files in that directory.  \nThe route is unauthenticated, so **any user can retrieve source files** without logging in.\n\n\u003e Limitation: the route only matches `/static/\u003cgroup\u003e/\u003cfilename\u003e` and rejects slashes inside `filename`, so it cannot traverse further to arbitrary system paths like `/etc/passwd`. It is limited to files inside the application package directory.\n\n### PoC\n1) Start an instance (example: Docker on port 5050)\n```\ndocker run -d --name cdio -p 127.0.0.1:5050:5000 -v cdio-data:/datastore cdio-local\n```\n\n2) Reproduce  \n**(URL-encoded traversal)**\n```\ncurl -i http://127.0.0.1:5050/static/%2e%2e/flask_app.py\n```\n\n**(curl path passthrough)**\n```\ncurl --path-as-is -i http://127.0.0.1:5050/static/../flask_app.py\n```\n\n3) Observe that the response body contains Python source code from `flask_app.py`.\n\n### Impact\n- **Vulnerability type:** Directory Traversal / Local File Read\n- **Affected users:** Anyone with network access (no authentication required)\n- **Scope:** Source files under `/app/changedetectionio`\n- **Security impact:** Internal logic exposure can aid further exploitation (Confidentiality: Low)",
  "id": "GHSA-9jj8-v89v-xjvw",
  "modified": "2026-07-20T19:06:55Z",
  "published": "2026-07-20T19:06:55Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/dgtlmoon/changedetection.io/security/advisories/GHSA-9jj8-v89v-xjvw"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-25527"
    },
    {
      "type": "WEB",
      "url": "https://github.com/dgtlmoon/changedetection.io/commit/9d38b4517364831889b5b0d7b3465fd060403fd4"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/dgtlmoon/changedetection.io"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/changedetection-io/PYSEC-2026-2124.yaml"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "changedetection.io is vulnerable to unauthenticated static path traversal"
}



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