giscus is a commenting system powered by GitHub Discussions. A bug in giscus' discussions creation API allowed an unauthorized user to create discussions on any repository where giscus is installed. This affects the server-side part of giscus, which is provided via http://giscus.app or your own self-hosted service. This vulnerability is fixed by the c43af7806e65adfcf4d0feeebef76dc36c95cb9a and 4b9745fe1a326ce08d69f8a388331bc993d19389 commits.
https://github.com/giscus/giscus/security/advisories/GHSA-w6vg-v24f-4vm3
https://github.com/giscus/giscus/commit/c43af7806e65adfcf4d0feeebef76dc36c95cb9a
https://github.com/giscus/giscus/commit/4b9745fe1a326ce08d69f8a388331bc993d19389