A local overflow exists in Exim. The mail daemon fails to properly filter input to some exim command line options, including -C and -F, resulting in an exploitable overflow. With a specially crafted request that includes a long (~32768 bytes) argument, an attacker can cause root compromise resulting in a loss of integrity.
Upgrade to version 3.35 or higher, as it has been reported to fix this vulnerability. An upgrade is required as there are no known workarounds.