In OpenSSH 7.9, due to accepting and displaying arbitrary stderr output from the server, a malicious server (or Man-in-The-Middle attacker) can manipulate the client output, for example to use ANSI control codes to hide additional files being transferred.

References

• https://nvd.nist.gov/vuln/detail/CVE-2019-6110
• https://cvsweb.openbsd.org/src/usr.bin/ssh/progressmeter.c
• https://cvsweb.openbsd.org/src/usr.bin/ssh/scp.c
• https://security.gentoo.org/glsa/201903-16
• https://security.netapp.com/advisory/ntap-20190213-0001/
• https://sintonen.fi/advisories/scp-client-multiple-vulnerabilities.txt
• https://www.exploit-db.com/exploits/46193/
• https://cert-portal.siemens.com/productcert/pdf/ssa-412672.pdf