Insufficient sanitization of environment variables passed to rsync can bypass the restrictions imposed by rssh, a restricted shell that should restrict users to perform only rsync operations, resulting in the execution of arbitrary shell commands.
seclists.org/fulldisclosure/2021/May/78
www.securityfocus.com/bid/106839
lists.debian.org/debian-lts-announce/2019/02/msg00007.html
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HO3MDU3AH5SLYBKHH5PJ6PHC63ASIF42/
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KR2OHTHMJVV4DO3HDRFQQZ5JENHDJQEN/
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/T42YYNWJZG422GATWAHAEK4A24OKY557/
security.gentoo.org/glsa/202007-29
tracker.debian.org/news/1026713/accepted-rssh-234-5deb9u2-source-amd64-into-stable-embargoed-stable/
usn.ubuntu.com/3946-1/
www.debian.org/security/2019/dsa-4382