14 DAY TRIAL // Canonical on Monday published two Ubuntu Security Notice (USN) advisories to inform users of Ubuntu 14.04 LTS and Ubuntu 12.04 LTS operating systems about the availability of new kernel updates.
A total of four security issues affect Ubuntu 14.04 LTS (Trusty Tahr) operating systems running the Linux 3.13.0 kernel, as well as official derivatives, including Kubuntu, Xubuntu, Lubuntu, etc. All supported architectures are affected, including 64-bit (amd64), 32-bit (i386), PowerPC (PPC), and PowerPC64 (PPC64).
The first and most important security flaw (CVE-2017-7482) fixed in this update was discovered by 石磊 in Linux kernel's RxRPC Kerberos 5 ticket handling code, which incorrectly verified metadata, allowing a remote attacker to either execute arbitrary code or crash the vulnerable system via a denial of service.
The second security issue fixed by this update is an integer overflow (CVE-2016-8405) discovered by Peter Pi in Linux kernel's colormap handling for frame buffer devices, which could allow a local attacker to expose sensitive information from kernel memory.
The third security flaw (CVE-2017-1000365) could allow a local attacker to execute arbitrary code if it used it in combination with another vulnerability as Linux kernel failed to properly restrict RLIMIT_STACK size, and the fourth security issue (CVE-2017-2618) could have allowed a local attacker to crash the system by causing a denial of service because SELinux incorrectly handled empty writes to /proc/pid/attr.
Users are urged to update their systems immediately
Canonical urges users of Ubuntu 14.04 LTS (Trusty Tahr) operating system running the Linux 3.13 kernel to update their installations as soon as possible to linux-image 3.13.0.126.136. A Trusty HWE (hardware enablement) kernel (linux-image-generic-lts-trusty 3.13.0.126.117) is also available for Ubuntu 12.04.5 LTS (Precise Pangolin) users using the Extended Security Maintenance (ESM) service.
To update your system, don't hesitate to follow the instructions provided by Canonical at https://wiki.ubuntu.com/Security/Upgrades, or fire up the Terminal app and run the "sudo apt-get update && sudo apt-get dist-upgrade" command. Don't forget to reboot your computer after installing the new kernel version, and remember to always keep your operating systems and apps up to date.