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.
https://github.com/FreshRSS/FreshRSS/security/advisories/GHSA-qw34-frg7-gf78
https://github.com/FreshRSS/FreshRSS/pull/8029
https://github.com/FreshRSS/FreshRSS/commit/7d4854a0a4f5665db599f18c34035786465639f3