CVE-2025-62780

A Stored Cross Site Scripting is present in the changedetection.io Watch update API due to unsufficient security checks.

Details

Tested on changedetection.io version v0.50.24

REPOSITORY                            TAG       IMAGE ID       CREATED        SIZE
ghcr.io/dgtlmoon/changedetection.io   latest    0367276509a0   23 hours ago   599MB

When a user tries to add an unsafe URL as a Watch in the changedetection.io UI, the action is blocked with the error message "Watch protocol is not permitted by SAFE_PROTOCOL_REGEX or incorrect URL format".
This is catched by the function validate_url(test_url).

def validate_url(test_url):
    # ...
    from .model.Watch import is_safe_url
    if not is_safe_url(test_url):
        # This should be wtforms.validators.
        raise ValidationError('Watch protocol is not permitted by SAFE_PROTOCOL_REGEX or incorrect URL format')

When instead the Watch API is used, this check is not performed resulting in unsafe URLs added as Watch.

PoC

Update an existing watch with an unsafe URL

curl -X PUT "http://example.site/api/v1/watch/1242e1c5-d59e-4352-0078-203a55b21282" \
  -H "x-api-key: XXX" \
  -H "Content-Type: application/json" \
  -d '{
    "url": "javascript:alert(document.domain)",
    "title": "XSS PoC",
    "paused": false
  }'

Credits

Edoardo Ottavianelli @edoardottt

Two scenarios are possibile:

1. An attacker can insert a new watch with an arbitrary URL which really points to a web page. Once the HTML content is retrieved, the attacker updates the URL with a JavaScript payload.
2. An attacker substitutes the URL in an existing watch with a new URL that is in reality a JavaScript payload.

When the user clicks on Preview and then on the malicious link, the JavaScript malicious code is executed.

Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.

CVE-2025-62780 has a CVSS score of 3.5 (Low). The vector is network-reachable, high privileges required, and user interaction required. 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. A fixed version is available (0.50.34); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2025-62780? CVE-2025-62780 is a low-severity cross-site scripting (XSS) vulnerability in changedetection.io (pip), affecting versions < 0.50.34. It is fixed in 0.50.34. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. How severe is CVE-2025-62780? CVE-2025-62780 has a CVSS score of 3.5 (Low). 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-2025-62780? changedetection.io (pip) versions < 0.50.34 is affected.
4. Is there a fix for CVE-2025-62780? Yes. CVE-2025-62780 is fixed in 0.50.34. Upgrade to this version or later.
5. Is CVE-2025-62780 exploitable, and should I be worried? Whether CVE-2025-62780 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-2025-62780 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-2025-62780? Upgrade changedetection.io to 0.50.34 or later.