CVE-2015-5600 Denial of service in n/a
Remote attackers can cause CPU exhaustion and facilitate brute-force attacks by sending a duplicative keyboard-interactive device list to OpenSSH.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2015-5600?
CVE-2015-5600 is a high-severity denial of service vulnerability in OpenSSH, published on 3 Aug 2015. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
The kbdint_next_device function in auth2-chall.c in sshd in OpenSSH through 6.9 does not properly restrict the processing of keyboard-interactive devices within a single connection, which makes it easier for remote attackers to conduct brute-force attacks or cause a denial of service (CPU consumption) via a long and duplicative list in the ssh -oKbdInteractiveDevices option, as demonstrated by a modified client that provides a different password for each pam element on this list.
Which versions are affected by CVE-2015-5600?
It affects 1 product.
Products include OpenSSH.
How do I fix CVE-2015-5600?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2015-5600 being exploited?
There is no known exploitation of CVE-2015-5600 in the wild and no public exploit code.
Public exploit code: 1 proofs of concept on GitHub.
Other vulnerabilities in OpenSSH
Sources
Also known as DEBIAN-CVE-2015-5600, GHSA-6x25-gfx2-5crp, MGASA-2015-0295, UBUNTU-CVE-2015-5600.