CVE-2019-6111

NameCVE-2019-6111
DescriptionAn issue was discovered in OpenSSH 7.9. Due to the scp implementation being derived from 1983 rcp, the server chooses which files/directories are sent to the client. However, the scp client only performs cursory validation of the object name returned (only directory traversal attacks are prevented). A malicious scp server (or Man-in-The-Middle attacker) can overwrite arbitrary files in the scp client target directory. If recursive operation (-r) is performed, the server can manipulate subdirectories as well (for example, to overwrite the .ssh/authorized_keys file).
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub code/issues, web search, more)
ReferencesDLA-1728-1, DSA-4387-1, DSA-4387-2
NVD severitymedium (attack range: remote)
Debian Bugs923486

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
openssh (PTS)jessie1:6.7p1-5+deb8u4vulnerable
jessie (security)1:6.7p1-5+deb8u8fixed
stretch (security), stretch1:7.4p1-10+deb9u6fixed
buster1:7.9p1-10fixed
bullseye, sid1:8.0p1-4fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
opensshsource(unstable)1:7.9p1-9medium923486
opensshsourcejessie1:6.7p1-5+deb8u8mediumDLA-1728-1
opensshsourcestretch1:7.4p1-10+deb9u6mediumDSA-4387-2

Notes

https://sintonen.fi/advisories/scp-client-multiple-vulnerabilities.txt
https://github.com/openssh/openssh-portable/commit/391ffc4b9d31fa1f4ad566499fef9176ff8a07dc
https://github.com/openssh/openssh-portable/commit/3d896c157c722bc47adca51a58dca859225b5874
For unstable partially fixed in 1:7.9p1-6, applied complete fix in 1:7.9p1-9.

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