There is a security problem in all versions prior to 2.6.1 that
affects only people running a read/write daemon WITHOUT using chroot.
If the user privs that such an rsync daemon is using is anything above
"nobody", you are at risk of someone crafting an attack that could
write a file outside of the module's "path" setting (where all its
files should be stored). Please either enable chroot or upgrade to
2.6.1. People not running a daemon, running a read-only daemon, or
running a chrooted daemon are totally unaffected.
Affects: 2.1AS 2.1AW 2.1ES 2.1WS [#122511]
Affects: 3AS 3ES 3WS 3Desktop [#122511]
Note that this has been in testing for a few weeks:
This silently made it out of testing. I just mailed the announcement.