ELA-94-1 openssh security update

scp vulnerabilities

Related CVEs CVE-2018-20685 CVE-2019-6109 CVE-2019-6111

Harry Sintonen from F-Secure Corporation discovered multiple vulnerabilities in OpenSSH, an implementation of the SSH protocol suite. All the vulnerabilities are found in the scp client implementing the SCP protocol.


Due to improper directory name validation, the scp client allows servers to
modify permissions of the target directory by using empty or dot directory


Due to missing character encoding in the progress display, the object name
can be used to manipulate the client output, for example to employ ANSI
codes to hide additional files being transferred.


Due to scp client insufficient input validation in path names sent by
the server, a malicious server can do arbitrary file overwrites in target
directory. If the recursive (-r) option is provided, the server can also
manipulate subdirectories as well.

The check added in this version can lead to a regression if the client and
the server behave differently in wildcard expansion rules. If the server is
trusted for that purpose, the check can be disabled with a new -T option to
the scp client.

For Debian 7 Wheezy, these problems have been fixed in version 1:6.0p1-4+deb7u11.

We recommend that you upgrade your openssh packages.

Further information about Extended LTS security advisories can be found at: https://deb.freexian.com/extended-lts/