In OpenSSH 7.9, scp.c in the scp client allows remote SSH servers to bypass intended access restrictions via the filename of . or an empty filename. The impact is modifying the permissions of the target directory on the client side.
https://access.redhat.com/errata/RHSA-2019:3702
https://cert-portal.siemens.com/productcert/pdf/ssa-412672.pdf
https://github.com/openssh/openssh-portable/commit/6010c0303a422a9c5fa8860c061bf7105eb7f8b2
https://lists.debian.org/debian-lts-announce/2019/03/msg00030.html
https://security.gentoo.org/glsa/201903-16
https://security.gentoo.org/glsa/202007-53
https://security.netapp.com/advisory/ntap-20190215-0001/
https://usn.ubuntu.com/3885-1/
https://www.debian.org/security/2019/dsa-4387
https://www.oracle.com/technetwork/security-advisory/cpuapr2019-5072813.html
https://www.oracle.com/technetwork/security-advisory/cpuoct2019-5072832.html