Provide references for CVE-2020-26891.
Where can I find more information about CVE-2020-26891?
References are available at: https://github.com/matrix-org/synapse/pull/8444, https://matrix.org/blog/2020/10/15/synapse-1-21-2-released-and-security-advisory, https://github.com/matrix-org/synapse/releases/tag/v1.21.2, https://github.com/matrix-org/synapse/security/advisories/GHSA-3x8c-fmpc-5rmq.