medium
5.5
CWE
203 200
Advisory Published
CVE Published
CVE Published
Updated

CVE-2020-27170: Infoleak

First published: Thu Mar 18 2021(Updated: )

A flaw was found in the Linux kernels eBPF verification code. By default accessing the eBPF verifier is only accessible to privileged users with CAP_SYS_ADMIN. A local user with the ability to insert eBPF instructions can use the eBPF verifier to abuse a spectre like flaw where they can infer all system memory.

Credit: cve@mitre.org

Affected SoftwareAffected VersionHow to fix
redhat/kernel-rt<0:3.10.0-1160.31.1.rt56.1169.el7
0:3.10.0-1160.31.1.rt56.1169.el7
redhat/kernel<0:3.10.0-1160.31.1.el7
0:3.10.0-1160.31.1.el7
IBM Data Risk Manager<=2.0.6
Linux Kernel<5.11.8
Red Hat Fedora=32
Red Hat Fedora=33
Red Hat Fedora=34
Ubuntu=14.04
Ubuntu=16.04
Ubuntu=18.04
Ubuntu=20.04
Debian Linux=9.0
debian/linux
5.10.223-1
5.10.234-1
6.1.129-1
6.1.135-1
6.12.22-1
6.12.25-1

Remedy

The default Red Hat Enterprise Linux kernel prevents unprivileged users from being able to use eBPF by the kernel.unprivileged_bpf_disabled sysctl. This would require a privileged user with CAP_SYS_ADMIN or root to be able to abuse this flaw reducing its attack space. For the Red Hat Enterprise Linux 7 the eBPF for unprivileged users is always disabled. For the Red Hat Enterprise Linux 8 to confirm the current state, inspect the sysctl with the command: # cat /proc/sys/kernel/unprivileged_bpf_disabled The setting of 1 would mean that unprivileged users can not use eBPF, mitigating the flaw. A kernel update will be required to mitigate the flaw for the root or users with CAP_SYS_ADMIN capabilities.

Remedy

https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.11.8

Remedy

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=f232326f6966cf2a1d1db7bc917a4ce5f9f55f76

Remedy

https://www.openwall.com/lists/oss-security/2021/03/19/2

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Reference Links

Parent vulnerabilities

(Appears in the following advisories)

Frequently Asked Questions

  • What is the severity of CVE-2020-27170?

    The severity of CVE-2020-27170 is classified as medium.

  • How do I fix CVE-2020-27170?

    To fix CVE-2020-27170, update to the latest kernel version that contains the patch for this vulnerability.

  • Which Linux kernel versions are affected by CVE-2020-27170?

    CVE-2020-27170 affects Linux kernel versions prior to 5.11.8.

  • Is CVE-2020-27170 exploitable remotely?

    CVE-2020-27170 is a local vulnerability and cannot be exploited remotely.

  • What types of systems are impacted by CVE-2020-27170?

    CVE-2020-27170 impacts systems running affected versions of the Linux kernel and certain distributions like Red Hat, Ubuntu, and Debian.

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