When a Response does not contain a Content-Type header, Symfony falls back to the format defined in the Accept header of the request, leading to a possible mismatch between the response's content and Content-Type header. When the response is cached, this can lead to a corrupted cache where the cached format is not the right one.
Symfony does not use the Accept header anymore to guess the Content-Type.
The patch for this issue is available here for the 4.4 branch.
I would like to thank Xavier Lacot from JoliCode for reporting & Yonel Ceruto and Tobias Schultze for fixing the issue.
{
"severity": "LOW",
"nvd_published_at": null,
"github_reviewed_at": "2020-03-30T19:28:58Z",
"github_reviewed": true,
"cwe_ids": [
"CWE-435"
]
}