An issue was discovered in Prosody before 0.11.9. It does not use a constant-time algorithm for comparing certain secret strings when running under Lua 5.2 or later. This can potentially be used in a timing attack to reveal the contents of secret strings to an attacker.
https://www.debian.org/security/2021/dsa-4916
https://security.gentoo.org/glsa/202105-15
https://lists.debian.org/debian-lts-announce/2021/06/msg00018.html
https://lists.debian.org/debian-lts-announce/2021/06/msg00016.html
https://blog.prosody.im/prosody-0.11.9-released/