- Switch to using a cryptographically-secure random number generator for token strings, ensuring they cannot be predicted by an attacker. Thanks to @opnsec for identifying and responsibly disclosing this issue! ([\#5133](https://github.com/matrix-org/synapse/issues/5133))
- Blacklist 0.0.0.0 and :: by default for URL previews. Thanks to @opnsec for identifying and responsibly disclosing this issue too! ([\#5134](https://github.com/matrix-org/synapse/issues/5134))
Richard van der Hoff