Details
### Summary
The Feed Reader front-end module passes RSS feed URLs from its configuration directly to `$this->feedIo->read($url)` without any scheme validation or private-IP blocklist. A backend user with module-edit permissions can configure an arbitrary URL pointing to internal network services, cloud-provider metadata endpoints, or loopback addresses, causing the server to fetch those resources unconditionally. Confirmed live: the server successfully reaches the internal MySQL database container and its own loopback Apache instance.
---
### Details
In `core-bundle/src/Controller/FrontendModule/FeedReaderController.php`, the `getResponse()` function iterates over the configured feed URLs and passes each one directly to the HTTP client with no validation:
```php
// Line 50-55
foreach (StringUtil::trimsplit('[\n\t ]', trim($model->rss_feed)) as $url) {
try {
$feed = $this->cache->get(
'feed_reader_'.$model->id.'_'.md5($url),
function (ItemInterface $item) use ($url, $model) {
$readerResult = $this->feedIo->read($url, new Feed()); // <-- no validation
```
The DCA field definition for `rss_feed` in `tl_module.php` carries no URL scheme or host validation:
```php
'eval' => array('mandatory'=>true, 'decodeEntities'=>true, 'style'=>'height:60px')
```
The HTTP client is wired as `@psr18.http_client` (Symfony HttpClient) with no SSRF protection configured (`NoPrivateNetworkHttpClient` is not used).
---
### Impact
This is a CWE-918 (SSRF) vulnerability. A backend user with module-edit access can:
1. **Enumerate internal network services** -- probe any IP/port on the internal network by observing response times and error messages
2. **Reach internal APIs** -- access unauthenticated services inside the Docker/Kubernetes network (databases, caches, admin panels)
3. **Steal cloud metadata credentials** -- on AWS, fetch `http://169.254.169.254/latest/meta-data/iam/security-credentials/` to obtain IAM role credentials (IMDSv1 has no authentication)
4. **Pivot to internal infrastructure** -- use the server as a proxy to interact with services not exposed to the public internet
Confirmed in live testing: the server successfully connected to the internal MySQL container (`172.19.0.3:3306`) and retrieved a full HTTP response from its own loopback interface (`127.0.0.1:80`).
---
### Remediation
1. **Use `NoPrivateNetworkHttpClient`** -- wrap the injected HTTP client with Symfony's built-in SSRF protection before passing it to feedIo:
```php
use Symfony\Component\HttpClient\NoPrivateNetworkHttpClient;
$safeClient = new NoPrivateNetworkHttpClient($this->httpClient);
```
This blocks all RFC-1918, loopback, and link-local addresses at the HTTP client level.
2. **Validate URL scheme and host** -- before calling `feedIo->read()`, parse the URL and reject anything that is not `http://` or `https://` with a public routable IP or hostname.
3. **Configure the DCA field** -- add `'rgxp' => 'url'` and a custom validation callback to `tl_module.rss_feed` to reject non-public URLs at save time.
EPSS — exploit probability
Low0.29%
estimated chance of real-world exploitation in the next 30 days — higher than 19.1% of every CVE FIRST.org scores
Refreshed 9/24/2026 — via FIRST.org's EPSS model, not CVSS — this measures likelihood of exploitation, not how severe it would be.
