A serious Linux privilege-escalation bug has been in the wild for nine years

The exploit is titled CVE-2016-5195, and it’s a privilege-escalation bug as opposed to a code-execution vulnerability, as Ars Technica reports. That makes it theoretically less serious, but nevertheless, researchers aren’t taking it lightly. In part, it’s considered a serious threat because it resides in a Linux kernel section that’s used by almost all Linux distributions. And the bug is apparently being actively used by malicious parties in the real world.

According to Dan Rosenberg, senior researcher at Azimuth Security, “It’s probably the most serious Linux local privilege escalation ever. The nature of the vulnerability lends itself to extremely reliable exploitation. This vulnerability has been present for nine years, which is an extremely long period of time.” As of right now, Linux distributions are in various stages of receiving patches, after an official patch was developed by the official Linux kernel maintainers.

The exploit in question is one that can allow an attacker to gain greater levels of control over a targeted machine. For example, a user with otherwise limited access to a web-hosting provider’s server can use the exploit to gain deeper shell access, and then leverage that access to attack other users of the server or even server admins. Privilege-escalation vulnerabilities can also be combined with other exploits, such as SQL injection bugs, to run malicious code that they would normally be unable to execute.

Linux developer Phil Oester was the first to discover the bug, as indicated on a site that provides more information on the exploit. For now, you’ll want to check in with the maintainers of your particular Linux distribution and see if a patch is available. If it is, then you’ll want to apply it immediately to avoid seeing your Linux system suffer an attack.