Information disclosure in Linux kernel - CVE-2021-21781

Vulnerability identifier: #VU54395

CSH Severity: Low

CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear

CVE-ID: CVE-2021-21781

CWE-ID: CWE-200

Exploitation vector: Local access

Exploit availability: No public exploit available

Affected software:
Linux kernel
SUSE MicroOS
Red Hat CodeReady Linux Builder for Power, little endian
Anolis OS
Red Hat CodeReady Linux Builder for ARM 64
Red Hat Enterprise Linux for ARM 64
Red Hat CodeReady Linux Builder for x86_64
Red Hat Enterprise Linux for x86_64
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux for IBM z Systems
Slackware Linux
SUSE Linux Enterprise Module for Public Cloud
SUSE Linux Enterprise High Availability
SUSE Linux Enterprise Module for Basesystem
SUSE Linux Enterprise Module for Development Tools
SUSE Linux Enterprise Module for Realtime
SUSE Linux Enterprise Workstation Extension
SUSE Linux Enterprise Module for Live Patching
SUSE Linux Enterprise Module for Legacy Software
openEuler
Migration Toolkit for Containers
Red Hat Advanced Cluster Management for Kubernetes
IBM Spectrum Protect Plus
kernel-livepatch-SLE15-SP2_Update_18-debugsource
kernel-livepatch-5_3_18-24_78-default-debuginfo
kernel-livepatch-5_3_18-24_78-default
kernel-livepatch-5_3_18-59_19-default
linux-4.4.301/kernel-modules
linux-4.4.301/kernel-huge
linux-4.4.301/kernel-generic
linux-4.4.301/kernel-headers
kernel-devel
kernel-headers
kernel-modules
kernel-modules-extra
kernel-tools
kernel-tools-libs
perf
python3-perf
kernel-abi-stablelists
kernel-doc
kernel-debug-modules-extra
kernel-debug-modules
kernel-debug-devel
kernel-debug-core
kernel-debug
kernel-cross-headers
kernel-core
kernel
bpftool
kernel (Red Hat package)
python2-perf
python2-perf-debuginfo
perf-debuginfo
kernel-debuginfo
kernel-debugsource
python3-perf-debuginfo
kernel-tools-devel
kernel-tools-debuginfo
bpftool-debuginfo
kernel-source
kernel-source-azure
kernel-devel-azure
kernel-azure
kernel-azure-debuginfo
kernel-azure-debugsource
kernel-azure-devel
kernel-azure-devel-debuginfo
kernel-syms-azure
kernel-preempt-devel
kernel-default-livepatch
kernel-preempt-debugsource
kernel-preempt-debuginfo
kernel-syms
kernel-obs-build-debugsource
kernel-obs-build
reiserfs-kmp-default-debuginfo
reiserfs-kmp-default
kernel-default-livepatch-devel
kernel-default
kernel-default-debuginfo
kernel-default-debugsource
kernel-default-extra
kernel-default-extra-debuginfo
kernel-preempt-extra
kernel-preempt-extra-debuginfo
kernel-preempt-devel-debuginfo
ocfs2-kmp-default
gfs2-kmp-default-debuginfo
gfs2-kmp-default
dlm-kmp-default-debuginfo
dlm-kmp-default
cluster-md-kmp-default-debuginfo
ocfs2-kmp-default-debuginfo
cluster-md-kmp-default
kernel-macros
kernel-preempt
kernel-default-devel-debuginfo
kernel-default-devel
kernel-docs
kernel-default-base
kernel-rt_debug-devel
kernel-source-rt
kernel-devel-rt
ocfs2-kmp-rt-debuginfo
ocfs2-kmp-rt
kernel-syms-rt
kernel-rt_debug-devel-debuginfo
kernel-rt_debug-debugsource
kernel-rt_debug-debuginfo
kernel-rt_debug
kernel-rt-devel
kernel-rt
kernel-rt-debuginfo
kernel-rt-debugsource
cluster-md-kmp-rt
cluster-md-kmp-rt-debuginfo
dlm-kmp-rt
dlm-kmp-rt-debuginfo
gfs2-kmp-rt
gfs2-kmp-rt-debuginfo
kernel-rt-devel-debuginfo
kernel-zfcpdump-debugsource
kernel-64kb-debuginfo
kernel-64kb-debugsource
kernel-64kb-devel
kernel-64kb-devel-debuginfo
kernel-zfcpdump
kernel-zfcpdump-debuginfo
kernel-64kb
Pixel

The vulnerability allows a local user to gain access to potentially sensitive information.

The vulnerability exists due to excessive data output in the ARM SIGPAGE functionality. A userland application can read the contents of the sigpage, which can leak kernel memory contents.

Install updates from vendor's website.

• https://www.talosintelligence.com/vulnerability_reports/TALOS-2021-1243