Incorrect Authorization Affecting openssh package, versions <1:7.9p1-5

Note: Versions mentioned in the description apply only to the upstream openssh package and not the openssh package as distributed by Ubuntu. See How to fix? for Ubuntu:20.04 relevant fixed versions and status.

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.

• http://people.ubuntu.com/~ubuntu-security/cve/CVE-2018-20685
• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-20685
• https://www.debian.org/security/2019/dsa-4387
• https://lists.debian.org/debian-lts-announce/2019/03/msg00030.html
• https://security-tracker.debian.org/tracker/CVE-2018-20685
• https://security.gentoo.org/glsa/202007-53
• https://security.gentoo.org/glsa/201903-16
• https://github.com/openssh/openssh-portable/commit/6010c0303a422a9c5fa8860c061bf7105eb7f8b2
• https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/scp.c.diff?r1=1.197&r2=1.198&f=h
• https://sintonen.fi/advisories/scp-client-multiple-vulnerabilities.txt
• https://security.netapp.com/advisory/ntap-20190215-0001/
• https://www.oracle.com/technetwork/security-advisory/cpuapr2019-5072813.html
• https://www.oracle.com/technetwork/security-advisory/cpuoct2019-5072832.html
• https://access.redhat.com/errata/RHSA-2019:3702
• https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-20685
• http://www.securityfocus.com/bid/106531
• https://usn.ubuntu.com/3885-1/
• https://cert-portal.siemens.com/productcert/pdf/ssa-412672.pdf