Symfony 4.3, 4.4.0 to 4.4.12, 5.0, and 5.1.0 to 5.1.4 versions of the Symfony HttpClient component are affected by this security issue.
The issue has been fixed in Symfony 4.4.13 and 5.1.5. Symfony 4.3 and 5.0 won't be patched as they are not maintained anymore.
CachingHttpClient class from the HttpClient Symfony componeny relies on
HttpCache class to handle requests.
HttpCache uses internal headers
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.
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