RHSA-2021:1267HighCVSS 7.8

Red Hat Security Advisory: kernel security and bug fix update

Published
April 20, 2021
Last Modified
July 30, 2026

🔗 CVE IDs covered (4)

CVE-2021-27363 →CVE-2021-27364 →CVE-2021-27365 →CVE-2020-14351 →

📋 Description

CVE-2020-14351 — kernel: performance counters race condition use-after-free CVE-2021-27363 — kernel: iscsi: unrestricted access to sessions and handles CVE-2021-27364 — kernel: out-of-bounds read in libiscsi module CVE-2021-27365 — kernel: heap buffer overflow in the iSCSI subsystem

🎯 Affected products100

  • Red Hat Enterprise Linux Server AUS (v. 7.4)
  • Red Hat Enterprise Linux Server E4S (v. 7.4)
  • Red Hat Enterprise Linux Server Optional AUS (v. 7.4)
  • Red Hat Enterprise Linux Server Optional E4S (v. 7.4)
  • Red Hat Enterprise Linux Server Optional TUS (v. 7.4)
  • Red Hat Enterprise Linux Server TUS (v. 7.4)
  • kernel-0:3.10.0-693.84.1.el7.ppc64le as a component of Red Hat Enterprise Linux Server E4S (v. 7.4)
  • kernel-0:3.10.0-693.84.1.el7.src as a component of Red Hat Enterprise Linux Server AUS (v. 7.4)
  • kernel-0:3.10.0-693.84.1.el7.src as a component of Red Hat Enterprise Linux Server E4S (v. 7.4)
  • kernel-0:3.10.0-693.84.1.el7.src as a component of Red Hat Enterprise Linux Server TUS (v. 7.4)
  • kernel-0:3.10.0-693.84.1.el7.x86_64 as a component of Red Hat Enterprise Linux Server AUS (v. 7.4)
  • kernel-0:3.10.0-693.84.1.el7.x86_64 as a component of Red Hat Enterprise Linux Server E4S (v. 7.4)
  • kernel-0:3.10.0-693.84.1.el7.x86_64 as a component of Red Hat Enterprise Linux Server TUS (v. 7.4)
  • kernel-abi-whitelists-0:3.10.0-693.84.1.el7.noarch as a component of Red Hat Enterprise Linux Server AUS (v. 7.4)
  • kernel-abi-whitelists-0:3.10.0-693.84.1.el7.noarch as a component of Red Hat Enterprise Linux Server E4S (v. 7.4)
  • kernel-abi-whitelists-0:3.10.0-693.84.1.el7.noarch as a component of Red Hat Enterprise Linux Server TUS (v. 7.4)
  • kernel-bootwrapper-0:3.10.0-693.84.1.el7.ppc64le as a component of Red Hat Enterprise Linux Server E4S (v. 7.4)
  • kernel-debug-0:3.10.0-693.84.1.el7.ppc64le as a component of Red Hat Enterprise Linux Server E4S (v. 7.4)
  • kernel-debug-0:3.10.0-693.84.1.el7.x86_64 as a component of Red Hat Enterprise Linux Server AUS (v. 7.4)
  • kernel-debug-0:3.10.0-693.84.1.el7.x86_64 as a component of Red Hat Enterprise Linux Server E4S (v. 7.4)
  • kernel-debug-0:3.10.0-693.84.1.el7.x86_64 as a component of Red Hat Enterprise Linux Server TUS (v. 7.4)
  • kernel-debug-debuginfo-0:3.10.0-693.84.1.el7.ppc64le as a component of Red Hat Enterprise Linux Server E4S (v. 7.4)
  • kernel-debug-debuginfo-0:3.10.0-693.84.1.el7.ppc64le as a component of Red Hat Enterprise Linux Server Optional E4S (v. 7.4)
  • kernel-debug-debuginfo-0:3.10.0-693.84.1.el7.x86_64 as a component of Red Hat Enterprise Linux Server AUS (v. 7.4)
  • kernel-debug-debuginfo-0:3.10.0-693.84.1.el7.x86_64 as a component of Red Hat Enterprise Linux Server E4S (v. 7.4)
  • kernel-debug-debuginfo-0:3.10.0-693.84.1.el7.x86_64 as a component of Red Hat Enterprise Linux Server Optional AUS (v. 7.4)
  • kernel-debug-debuginfo-0:3.10.0-693.84.1.el7.x86_64 as a component of Red Hat Enterprise Linux Server Optional E4S (v. 7.4)
  • kernel-debug-debuginfo-0:3.10.0-693.84.1.el7.x86_64 as a component of Red Hat Enterprise Linux Server Optional TUS (v. 7.4)
  • kernel-debug-debuginfo-0:3.10.0-693.84.1.el7.x86_64 as a component of Red Hat Enterprise Linux Server TUS (v. 7.4)
  • kernel-debug-devel-0:3.10.0-693.84.1.el7.ppc64le as a component of Red Hat Enterprise Linux Server Optional E4S (v. 7.4)
  • +70 more not shown

✅ Remediation

For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 The system must be rebooted for this update to take effect. Workaround: While there is no way to disable the perf subsystem on Linux systems, reducing or removing users access to the perf events can effectively mitigate this flaw. Upstream kernel documentation has been written regarding this mechanism: https://www.kernel.org/doc/html/latest/admin-guide/perf-security.html. Workaround: The LIBISCSI module will be auto-loaded when required, its use can be disabled by preventing the module from loading with the following instructions: # echo "install libiscsi /bin/true" >> /etc/modprobe.d/disable-libiscsi.conf The system will need to be restarted if the libiscsi modules are loaded. In most circumstances, the libiscsi kernel modules will be unable to be unloaded while any network interfaces are active and the protocol is in use. If the system requires iscsi to work correctly, this mitigation may not be suitable. If you need further assistance, see KCS article https://access.redhat.com/solutions/41278 or contact Red Hat Global Support Services. Workaround: The LIBISCSI module will be auto-loaded when required, its use can be disabled by preventing the module from loading with the following instructions: ~~~ # echo "install libiscsi /bin/true" >> /etc/modprobe.d/disable-libiscsi.conf ~~~ The system will need to be restarted if the libiscsi modules are loaded. In most circumstances, the libiscsi kernel modules will be unable to be unloaded while any network interfaces are active and the protocol is in use. If the system requires iscsi to work correctly, this mitigation may not be suitable. If you need further assistance, see KCS article https://access.redhat.com/solutions/41278 or contact Red Hat Global Support Services.

🔗 References (7)