FreshRSS globally denies access to feed via proxy modifying to 429 Retry-After

FreshRSS is a free, self-hostable RSS aggregator. From version 1.27.0 to before 1.28.0, An attacker could globally deny access to feeds via proxy modifying to 429 Retry-After for a large list of feeds on given instance, making it unusable for majority of users. This issue has been patched in version 1.28.0.