RHSA-2021:1531HighCVSS 8.1

Red Hat Security Advisory: kernel security and bug fix update

Published
May 11, 2021
Last Modified
July 30, 2026

🔗 CVE IDs covered (7)

CVE-2021-27364 →CVE-2021-27365 →CVE-2019-19532 →CVE-2020-25211 →CVE-2020-25705 →CVE-2020-28374 →CVE-2021-27363 →

📋 Description

CVE-2019-19532 — kernel: malicious USB devices can lead to multiple out-of-bounds write CVE-2020-25211 — kernel: Local buffer overflow in ctnetlink_parse_tuple_filter in net/netfilter/nf_conntrack_netlink.c CVE-2020-25705 — kernel: ICMP rate limiting can be used for DNS poisoning attack CVE-2020-28374 — kernel: SCSI target (LIO) write to any block on ILO backstore 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 products124

  • Red Hat Enterprise Linux ComputeNode EUS (v. 7.7)
  • Red Hat Enterprise Linux ComputeNode Optional EUS (v. 7.7)
  • Red Hat Enterprise Linux Server EUS (v. 7.7)
  • Red Hat Enterprise Linux Server Optional EUS (v. 7.7)
  • bpftool-0:3.10.0-1062.49.1.el7.ppc64 as a component of Red Hat Enterprise Linux Server EUS (v. 7.7)
  • bpftool-0:3.10.0-1062.49.1.el7.ppc64le as a component of Red Hat Enterprise Linux Server EUS (v. 7.7)
  • bpftool-0:3.10.0-1062.49.1.el7.s390x as a component of Red Hat Enterprise Linux Server EUS (v. 7.7)
  • bpftool-0:3.10.0-1062.49.1.el7.x86_64 as a component of Red Hat Enterprise Linux ComputeNode EUS (v. 7.7)
  • bpftool-0:3.10.0-1062.49.1.el7.x86_64 as a component of Red Hat Enterprise Linux Server EUS (v. 7.7)
  • bpftool-debuginfo-0:3.10.0-1062.49.1.el7.ppc64 as a component of Red Hat Enterprise Linux Server EUS (v. 7.7)
  • bpftool-debuginfo-0:3.10.0-1062.49.1.el7.ppc64 as a component of Red Hat Enterprise Linux Server Optional EUS (v. 7.7)
  • bpftool-debuginfo-0:3.10.0-1062.49.1.el7.ppc64le as a component of Red Hat Enterprise Linux Server EUS (v. 7.7)
  • bpftool-debuginfo-0:3.10.0-1062.49.1.el7.ppc64le as a component of Red Hat Enterprise Linux Server Optional EUS (v. 7.7)
  • bpftool-debuginfo-0:3.10.0-1062.49.1.el7.s390x as a component of Red Hat Enterprise Linux Server EUS (v. 7.7)
  • bpftool-debuginfo-0:3.10.0-1062.49.1.el7.x86_64 as a component of Red Hat Enterprise Linux ComputeNode EUS (v. 7.7)
  • bpftool-debuginfo-0:3.10.0-1062.49.1.el7.x86_64 as a component of Red Hat Enterprise Linux ComputeNode Optional EUS (v. 7.7)
  • bpftool-debuginfo-0:3.10.0-1062.49.1.el7.x86_64 as a component of Red Hat Enterprise Linux Server EUS (v. 7.7)
  • bpftool-debuginfo-0:3.10.0-1062.49.1.el7.x86_64 as a component of Red Hat Enterprise Linux Server Optional EUS (v. 7.7)
  • kernel-0:3.10.0-1062.49.1.el7.ppc64 as a component of Red Hat Enterprise Linux Server EUS (v. 7.7)
  • kernel-0:3.10.0-1062.49.1.el7.ppc64le as a component of Red Hat Enterprise Linux Server EUS (v. 7.7)
  • kernel-0:3.10.0-1062.49.1.el7.s390x as a component of Red Hat Enterprise Linux Server EUS (v. 7.7)
  • kernel-0:3.10.0-1062.49.1.el7.src as a component of Red Hat Enterprise Linux ComputeNode EUS (v. 7.7)
  • kernel-0:3.10.0-1062.49.1.el7.src as a component of Red Hat Enterprise Linux Server EUS (v. 7.7)
  • kernel-0:3.10.0-1062.49.1.el7.x86_64 as a component of Red Hat Enterprise Linux ComputeNode EUS (v. 7.7)
  • kernel-0:3.10.0-1062.49.1.el7.x86_64 as a component of Red Hat Enterprise Linux Server EUS (v. 7.7)
  • kernel-abi-whitelists-0:3.10.0-1062.49.1.el7.noarch as a component of Red Hat Enterprise Linux ComputeNode EUS (v. 7.7)
  • kernel-abi-whitelists-0:3.10.0-1062.49.1.el7.noarch as a component of Red Hat Enterprise Linux Server EUS (v. 7.7)
  • kernel-bootwrapper-0:3.10.0-1062.49.1.el7.ppc64 as a component of Red Hat Enterprise Linux Server EUS (v. 7.7)
  • kernel-bootwrapper-0:3.10.0-1062.49.1.el7.ppc64le as a component of Red Hat Enterprise Linux Server EUS (v. 7.7)
  • kernel-debug-0:3.10.0-1062.49.1.el7.ppc64 as a component of Red Hat Enterprise Linux Server EUS (v. 7.7)
  • +94 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: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability. Workaround: To mitigate this issue, prevent module nf_conntrack_netlink from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically. Alternatively, if nf_conntrack_netlink is being used, on Red Hat Enterprise Linux 8, you can disable unprivileged user namespaces by setting user.max_user_namespaces to 0: # echo "user.max_user_namespaces=0" > /etc/sysctl.d/userns.conf # sysctl -p /etc/sysctl.d/userns.conf Workaround: The mitigation is to disable ICMP destination unreachable messages. The commands to disable UDP port unreachable ICMP reply messages: iptables -I OUTPUT -p icmp --icmp-type destination-unreachable -j DROP service iptables save For additional information about "service iptables save" please read https://access.redhat.com/solutions/1597703 It is not recommended to apply this rule if host being used as forwarder (router) of IP packets. Or it is possible to use this firewall-cmd instead of iptables and the result is similar: firewall-cmd --permanent --direct --add-rule ipv4 filter OUTPUT 0 -p icmp --icmp-type destination-unreachable -j DROP 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 (10)