Provide references for CVE-2021-21276.
Where can I find more information about CVE-2021-21276?
References are available at: https://github.com/cydrobolt/polr/security/advisories/GHSA-vg6w-8w9v-xxqc, https://github.com/cydrobolt/polr/commit/b1981709908caf6069b4a29dad3b6739c322c675, https://github.com/cydrobolt/polr/releases/tag/2.3.0, http://packetstormsecurity.com/files/171743/POLR-URL-2.3.0-Shortener-Admin-Takeover.html.