Use-after-free in Linux kernel - CVE-2018-20856

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Main Vulnerability Database Vulnerabilities #VU19568

Use-after-free in Linux kernel - CVE-2018-20856

Published: July 31, 2019


Vulnerability identifier: #VU19568
CSH Severity: Low
CVSS v4: 4.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2018-20856
CWE-ID: CWE-416
Exploitation vector: Local access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a local attacker to execute arbitrary code on a targeted system.

The vulnerability exists due to a use-after-free error when the "__blk_drain_queue()" function in the "block/blk-core.c" file mishandles error cases. A local authenticated attacker can access the system and execute an application that submits malicious input, cause a use-after-free memory operation error and execute arbitrary code on the targeted system.

Successful exploitation of the vulnerability may allow an attacker to compromise vulnerable system.


Affected software

Linux kernel
Red Hat Enterprise Linux for IBM System z (Structure A)
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux for Scientific Computing
Red Hat Enterprise Linux for Power, big endian
Red Hat Enterprise Linux for Real Time
Red Hat Enterprise Linux for IBM z Systems
Red Hat Enterprise Linux for Power 9
Red Hat Enterprise Linux Server
Red Hat Enterprise Linux for ARM 64
Red Hat Enterprise Linux for Real Time for NFV
Red Hat Enterprise Linux Desktop
Red Hat Enterprise Linux Workstation
Red Hat Enterprise Linux Server - TUS
Red Hat Enterprise Linux Server - AUS
Red Hat Enterprise Linux for Power, big endian - Extended Update Support
Red Hat Enterprise Linux EUS Compute Node
Red Hat Enterprise Linux for IBM z Systems - Extended Update Support
Red Hat Enterprise Linux for x86_64 - Extended Update Support
Red Hat Enterprise Linux for Power, little endian - Extended Update Support
Red Hat Enterprise Linux for x86_64
Red Hat Virtualization Host - Extended Update Support 4.2 for RHEL
Red Hat Enterprise Linux for Power
Slackware Linux

MRG Realtime
kernel (Red Hat package)
kernel-rt (Red Hat package)
Red Hat Enterprise Linux Server for x86_64 - Update Services for SAP Solutions
Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions
kpatch-patch-3_10_0-1062_1_2 (Red Hat package)
kpatch-patch-3_10_0-1062_1_1 (Red Hat package)
kpatch-patch-3_10_0-1062 (Red Hat package)
kernel-alt (Red Hat package)
Red Hat Virtualization Host

How to mitigate CVE-2018-20856

Install updates from vendor's website.

Linux kernel - update to 4.18.7
kernel (Red Hat package) - addressed in versions 3.10.0-693.62.1.el7, 3.10.0-957.46.1.el7, 3.10.0-1062.4.1.el7
kernel-rt (Red Hat package) - addressed in versions 3.10.0-693.62.1.rt56.659.el6rt, 3.10.0-1062.4.1.rt56.1027.el7
kpatch-patch-3_10_0-1062_1_2 (Red Hat package) - update to 1-3.el7
kpatch-patch-3_10_0-1062_1_1 (Red Hat package) - update to 1-4.el7
kpatch-patch-3_10_0-1062 (Red Hat package) - update to 1-5.el7
kernel-alt (Red Hat package) - update to 4.14.0-115.14.1.el7a

External References

Related Security Bulletins