External service lookups for a number of protocols were vulnerable to a time-of-check/time-of-use (TOCTOU) weakness, involving the JDK DNS cache. Attackers that were timing DNS cache expiry correctly were able to inject configuration that would bypass existing network deny-lists. Attackers could exploit this weakness to discover the existence of restricted network infrastructure and service availability. Improvements were made to include deny-lists not only during the check of the provided connection data, but also during use. No publicly available exploits are known.

Attackers with access to user accounts can inject arbitrary control characters to SIEVE mail-filter rules. This could be abused to access SIEVE extension that are not allowed by App Suite or to inject rules which would break per-user filter processing, requiring manual cleanup of such rules. We have added sanitization to all mail-filter APIs to avoid forwardning control characters to subsystems. No publicly available exploits are known.