CVE-2020-24394: High severity Linux Linux kernel vulnerability

Published Jun 5, 2020
·
Updated

A vulnerability was found in NFSv4.2 in the Linux kernel, where a server fails to apply umask correctly when creating a new object on filesystem without ACL support (for example, ext4 with the "noacl" mount option). This flaw could allow a local attacker with a user privilege to a kernel information leak problem.

References: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=962254 https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=22cf8419f1319ff87ec759d0ebdff4cbafaee832

Other sources

A vulnerability was found in NFSv4.2 in the Linux kernel, where a server fails to correctly apply umask when creating a new object on filesystem without ACL support (for example, ext4 with the "noacl" mount option). This flaw allows a local attacker with a user privilege to cause a kernel information leak problem.

In the Linux kernel before 5.7.8, fs/nfsd/vfs.c (in the NFS server) can set incorrect permissions on new filesystem objects when the filesystem lacks ACL support, aka CID-22cf8419f131. This occurs because the current umask is not considered.

Affected Software

21 affected componentsFixes available
redhat/kernel-rt<0:3.10.0-1160.11.1.rt56.1145.el7
0:3.10.0-1160.11.1.rt56.1145.el7
redhat/kernel<0:3.10.0-1160.11.1.el7
0:3.10.0-1160.11.1.el7
redhat/kernel<0:3.10.0-693.82.1.el7
0:3.10.0-693.82.1.el7
redhat/kernel<0:3.10.0-957.70.1.el7
0:3.10.0-957.70.1.el7
redhat/kernel<0:3.10.0-1062.45.1.el7
0:3.10.0-1062.45.1.el7
redhat/kernel-rt<0:4.18.0-305.rt7.72.el8
0:4.18.0-305.rt7.72.el8
redhat/kernel<0:4.18.0-305.el8
0:4.18.0-305.el8
Linux Linux kernel<5.7.8
Canonical Ubuntu Linux=14.04
Canonical Ubuntu Linux=16.04
Canonical Ubuntu Linux=18.04
Canonical Ubuntu Linux=20.04
openSUSE Leap=15.1
Oracle SD-WAN Edge=8.2
Starwindsoftware Starwind Virtual San Vsphere=v8-build12533
Starwindsoftware Starwind Virtual San Vsphere=v8-build12658
Starwindsoftware Starwind Virtual San Vsphere=v8-build12859
Starwindsoftware Starwind Virtual San Vsphere=v8-build13170
Starwindsoftware Starwind Virtual San Vsphere=v8-build13586
Starwindsoftware Starwind Virtual San Vsphere=v8-build13861
debian/linux
5.10.223-15.10.262-16.1.176-16.1.180-16.12.94-16.12.101-17.1.8-17.1.8-2

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade redhat/kernel-rt to a version that resolves this vulnerability.

    Fixed in 0:3.10.0-1160.11.1.rt56.1145.el7
  2. Upgrade

    Upgrade redhat/kernel to a version that resolves this vulnerability.

    Fixed in 0:3.10.0-1160.11.1.el7
  3. Upgrade

    Upgrade redhat/kernel to a version that resolves this vulnerability.

    Fixed in 0:3.10.0-693.82.1.el7
  4. Upgrade

    Upgrade redhat/kernel to a version that resolves this vulnerability.

    Fixed in 0:3.10.0-957.70.1.el7
  5. Upgrade

    Upgrade redhat/kernel to a version that resolves this vulnerability.

    Fixed in 0:3.10.0-1062.45.1.el7
  6. Upgrade

    Upgrade redhat/kernel-rt to a version that resolves this vulnerability.

    Fixed in 0:4.18.0-305.rt7.72.el8
  7. Upgrade

    Upgrade redhat/kernel to a version that resolves this vulnerability.

    Fixed in 0:4.18.0-305.el8
  8. Upgrade

    Upgrade debian/linux to a version that resolves this vulnerability.

    Fixed in 5.10.223-1Fixed in 5.10.262-1Fixed in 6.1.176-1Fixed in 6.1.180-1Fixed in 6.12.94-1Fixed in 6.12.101-1Fixed in 7.1.8-1Fixed in 7.1.8-2
  9. Upgrade

    Upgrade Linux kernel to a version that resolves this vulnerability.

    Fixed in 5.7.8Patch CID-22cf8419f131
  10. Compensating control

    Because no mitigation is available per the provided text, restrict unprivileged (local) user access/attack surface on affected systems to reduce the chance a local attacker can trigger the kernel information leak.

Event History

Jun 5, 2020
CVE Published
12:00 AM
Aug 17, 2020
Data Sourced
via Red Hat·04:34 AM
DescriptionSeverityAffected Software
Aug 19, 2020
CVE Published
via MITRE·12:00 AM
Data Sourced
via MITRE·12:00 AM
Description
Data Sourced
via NVD·01:15 PM
RemedyDescriptionSeverityWeaknessAffected Software
Jan 11, 2024
Data Sourced
via Launchpad·11:45 PM
Description
Aug 15, 2026
Data Sourced
via Ubuntu·11:20 AM
RemedyDescriptionSeverityAffected Software
Aug 16, 2026
Data Sourced
via Debian·11:23 AM
DescriptionAffected Software

Parent advisories

This vulnerability appears in the following advisories.

Frequently Asked Questions

1

What is the severity of CVE-2020-24394?

CVE-2020-24394 has a severity rating that can allow local attackers to access kernel information due to improper umask application.

2

How do I fix CVE-2020-24394?

To fix CVE-2020-24394, apply the security updates provided in the corresponding kernel packages from your Linux distribution.

3

Which Linux kernel versions are affected by CVE-2020-24394?

CVE-2020-24394 affects multiple versions of the Linux kernel, specifically versions up to 5.7.8.

4

Can CVE-2020-24394 be exploited remotely?

CVE-2020-24394 cannot be exploited remotely as it requires local user privileges to be effective.

5

What types of systems are vulnerable to CVE-2020-24394?

Systems running specific versions of Red Hat kernel, Ubuntu, and other distributions utilizing NFSv4.2 without ACL support are vulnerable to CVE-2020-24394.

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