CachingHttpClient class from the HttpClient Symfony component relies on the
HttpCache class to handle requests.
HttpCache uses internal headers like
X-Body-File to control the restoration of cached responses. The class was initially written with surrogate caching and ESI support in mind (all HTTP calls come from a trusted backend in that scenario). But when used by
CachingHttpClient and if an attacker can control the response for a request being made by the
CachingHttpClient, remote code execution is possible.
HTTP headers designed for internal use in
HttpCache are now stripped from remote responses before being passed to
The patch for this issue is available here for the 4.4 branch.
I would like to thank Matthias Pigulla (webfactory GmbH) for reporting and fixing the issue.