Updates released on Wednesday for the Ubuntu operating system address several vulnerabilities in the Linux kernel, including ones that can be exploited for denial-of-service (DoS) attacks and arbitrary code execution.
A total of eight Linux kernel vulnerabilities have been patched in various Ubuntu 14 and 15 variants, including Utopic Unicorn, Wily Werewolf, Trusty Tahr and the Raspberry Pi 2 version.
Four of these vulnerabilities have been found to affect Ubuntu 14.04 LTS (long term support). One of them is a use-after-free flaw in the CXGB3 kernel driver (CVE-2015-8812) that can be exploited by a local attacker to crash the system and possibly even execute arbitrary code.
The issue, reported by Venkatesh Pottem of Red Hat Engineering, is triggered when the network is congested.
Another vulnerability patched by Ubuntu was discovered by Xiaofei Rex Guo. He discovered that an attacker could disrupt the integrity of the system by exploiting a timing side channel vulnerability in the Linux Extended Verification Module (EVM). The flaw has been assigned the identifier CVE-2016-2085.
A DoS vulnerability, tracked as CVE-2016-2550, has been identified by David Herrmann. The security hole allows a local, unauthenticated attacker to exhaust resources and cause a DoS condition due to the fact that the kernel incorrectly accounts file descriptors to the original opener for in-flight file descriptors sent over a Unix domain socket.
Another resource exhaustion issue patched by Ubuntu has been found by Tetsuo Handa. Handa discovered that the kernel did not enforce limits on the amount of data allocated to buffer pipes (CVE-2016-2847).
The vulnerabilities addressed by Ubuntu have also been fixed in Debian. Some of them also affect Red Hat products, but Red Hat has classified them as having low or medium severity and has yet to release patches.
In January, Israel-based security startup Perception Point reported discovering a local privilege escalation vulnerability in the Linux kernel that exposed tens of millions of Linux PCs and servers. The flaw, found in version 3.8 and later of the Linux kernel, allows an attacker to achieve kernel code execution and gain root privileges on the targeted system.
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