CVE-2026-89653

In the Linux kernel, the following vulnerability has been resolved:

ceph: reject export_targets ranks >= CEPH_MAX_MDS in mdsmap decode

MDSMap export_targets entries are monitor controlled. check_new_map()

uses each entry as a bit number in a fixed stack bitmap, so a rank

outside the protocol namespace can make set_bit() write past the end of

the array.

Reject ranks outside CEPH_MAX_MDS while decoding the map. Do not

validate against possible_max_rank here because maps may legitimately

reference ranks beyond a temporarily reduced max_mds.