systemd 250 and 251 allows local users to achieve a systemd-coredump deadlock by triggering a crash that has a long backtrace. This occurs in parseelfobject in shared/elf-util.c. The exploitation methodology is to crash a binary calling the same function recursively, and put it in a deeply nested directory to make its backtrace large enough to cause the deadlock. This must be done 16 times when MaxConnections=16 is set for the systemd/units/systemd-coredump.socket file.

An off-by-one Error issue was discovered in Systemd in formattimespan() function of time-util.c. An attacker could supply specific values for time and accuracy that leads to buffer overrun in formattimespan(), leading to a Denial of Service.