CVE-2019-19447: Use After Free

Published Dec 8, 2019
·
Updated

A flaw was found in the Linux kernel's ext4unlink function. An attacker could corrupt memory or escalate privileges when deleting a file from a recently unmounted specially crafted ext4 filesystem, including local, USB, and iSCSI.

Other sources

A user with permissions to mount and unmount a crafted ext4 file system, via any transport mechanism (local, USB, ISCSI) can lead to a use-after-free when attempting to delete a directory after the disk has been umounted.

This can lead to possible memory corruption and privilege escalation.

External Reference:

https://github.com/bobfuzzer/CVE/tree/master/CVE-2019-19447 https://bugzilla.kernel.org/showbug.cgi?id=205433

Red Hat

In the Linux kernel 5.0.21, mounting a crafted ext4 filesystem image, performing some operations, and unmounting can lead to a use-after-free in ext4putsuper in fs/ext4/super.c, related to dumporphanlist in fs/ext4/super.c.

Affected Software

21 affected componentsFixes available
redhat/kernel-rt<0:3.10.0-1160.rt56.1131.el7
0:3.10.0-1160.rt56.1131.el7
redhat/kernel-alt<0:4.14.0-115.21.2.el7a
0:4.14.0-115.21.2.el7a
redhat/kernel<0:3.10.0-1160.el7
0:3.10.0-1160.el7
redhat/kernel<0:3.10.0-693.81.1.el7
0:3.10.0-693.81.1.el7
redhat/kernel<0:3.10.0-957.65.1.el7
0:3.10.0-957.65.1.el7
redhat/kernel<0:3.10.0-1062.40.1.el7
0:3.10.0-1062.40.1.el7
redhat/kernel-rt<0:4.18.0-240.rt7.54.el8
0:4.18.0-240.rt7.54.el8
redhat/kernel<0:4.18.0-240.el8
0:4.18.0-240.el8
Linux Linux kernel>=2.6.12<3.16.82
Linux Linux kernel>=3.17<4.4.208
Linux Linux kernel>=4.5.0<4.9.208
Linux Linux kernel>=4.10<4.14.159
Linux Linux kernel>=4.15<4.19.90
Linux Linux kernel>=4.20<5.3.17
Linux Linux kernel>=5.4<5.4.4
NetApp Active Iq Unified Manager Vmware Vsphere
NetApp Cloud Backup
NetApp Data Availability Services
NetApp Hci Baseboard Management Controller=h610s
NetApp Steelstore Cloud Integrated Storage
NetApp Solidfire Baseboard Management Controller

Remediation

Information

Ext4 filesytems are built into the kernel so it is not possible to prevent the kernel module from loading. However, this flaw can be prevented by disallowing mounting of untrusted filesystems. As mounting is a privileged operation, (except for device hotplug) removing the ability for mounting and unmounting will prevent this flaw from being exploited.

Event History

Dec 8, 2019
CVE Published
via MITRE·12:48 AM
Data Sourced
via MITRE·12:48 AM
Description
Dec 10, 2019
Data Sourced
via Red Hat·11:37 AM
DescriptionSeverityAffected Software
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Frequently Asked Questions

1

What is CVE-2019-19447?

CVE-2019-19447 is a vulnerability in the Linux kernel's ext4_unlink function that allows an attacker to corrupt memory or escalate privileges when deleting a file from a specially crafted ext4 filesystem.

2

How severe is CVE-2019-19447?

CVE-2019-19447 has a severity rating of 7.8, which is considered high.

3

Which software versions are affected by CVE-2019-19447?

CVE-2019-19447 affects Linux kernel versions 5.0.21 and earlier.

4

How can I fix CVE-2019-19447?

To fix CVE-2019-19447, you should update your affected Linux kernel to version 5.0.22 or later.

5

Are there any references for CVE-2019-19447?

Yes, you can find more information about CVE-2019-19447 on the following links: [link1](https://github.com/bobfuzzer/CVE/tree/master/CVE-2019-19447), [link2](https://bugzilla.kernel.org/show_bug.cgi?id=205433), [link3](https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=1781680).

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