In rsync 3.0.1 through 3.4.1, receive_xattr relies on an untrusted length value during a qsort call, leading to a receiver use-after-free. The victim must run rsync with -X (aka --xattrs). On Linux, many (but not all) common configurations are vulnerable. Non-Linux platforms are more widely vulnerable.
3.2.7-0ubuntu0.22.04.63.2.7-1ubuntu1.43.4.1+ds1-5ubuntu1.23.4.1+ds1-7ubuntu0.23.1.0-2ubuntu0.4+esm33.1.1-3ubuntu1.3+esm53.1.2-2.1ubuntu1.6+esm33.1.3-8ubuntu0.9+esm1Exploitability
AV:LAC:LPR:NUI:RScope
S:UImpact
C:HI:HA:HCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H