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A use-after-free vulnerability was found in the Linux kernel's IPv6 FIB rule lookup path. In fib6_rule_suppress(), when a route is suppressed and released via ip6_rt_put_flags(), the res->rt6 pointer is not cleared. If no later rule supplies a replacement route, fib6_rule_lookup() returns the stale (freed) rt6_info to its caller. The subsequent dst_release() then operates on freed memory, hitting rcuref_put_slowpath(). A local attacker who can configure IPv6 routing/FIB rules could trigger this to cause a denial of service (kernel crash) or potentially escalate privileges.
Upstream advisory: https://lore.kernel.org/linux-cve-announce/2026082100-CVE-2026-74581-47ca@gregkh/T/#u
The proposed mitigation does not appear to be applicable to the affected RHEL kernels because IPv6 is built directly into the kernel (`CONFIG_IPV6=y`), rather than provided as a loadable kernel module. Therefore, the following configuration cannot prevent the IPv6 subsystem from being loaded: install ipv6 /bin/true blacklist ipv6 Since there is no `ipv6.ko` module to blacklist when `CONFIG_IPV6=y`, this mitigation would not disable the vulnerable IPv6 code path. A kernel command-line parameter such as: ipv6.disable=1 would appear to be a more appropriate mitigation for completely disabling IPv6 on these kernels. Could you please confirm whether the current mitigation guidance is correct for RHEL kernels built with `CONFIG_IPV6=y`?
This issue has been addressed in the following products: Red Hat Enterprise Linux 9 Via RHSA-2026:59723 https://access.redhat.com/errata/RHSA-2026:59723
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On Via RHSA-2026:59994 https://access.redhat.com/errata/RHSA-2026:59994
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions Via RHSA-2026:60438 https://access.redhat.com/errata/RHSA-2026:60438
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions Via RHSA-2026:60437 https://access.redhat.com/errata/RHSA-2026:60437
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On Via RHSA-2026:60485 https://access.redhat.com/errata/RHSA-2026:60485
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions Via RHSA-2026:60484 https://access.redhat.com/errata/RHSA-2026:60484
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.6 Extended Update Support Via RHSA-2026:60486 https://access.redhat.com/errata/RHSA-2026:60486
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions Red Hat Enterprise Linux 8.8 Telecommunications Update Service Via RHSA-2026:61932 https://access.redhat.com/errata/RHSA-2026:61932
This issue has been addressed in the following products: Red Hat Enterprise Linux 10.0 Extended Update Support Via RHSA-2026:62609 https://access.redhat.com/errata/RHSA-2026:62609
This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2026:63013 https://access.redhat.com/errata/RHSA-2026:63013
This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2026:63014 https://access.redhat.com/errata/RHSA-2026:63014
This issue has been addressed in the following products: Red Hat Enterprise Linux 10 Via RHSA-2026:63128 https://access.redhat.com/errata/RHSA-2026:63128
This issue has been addressed in the following products: NVIDIA for RHEL 10 Via RHSA-2026:72059 https://access.redhat.com/errata/RHSA-2026:72059
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions Via RHSA-2026:72628 https://access.redhat.com/errata/RHSA-2026:72628
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions Via RHSA-2026:72627 https://access.redhat.com/errata/RHSA-2026:72627
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions Via RHSA-2026:72630 https://access.redhat.com/errata/RHSA-2026:72630
This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2026:72629 https://access.redhat.com/errata/RHSA-2026:72629
This issue has been addressed in the following products: Red Hat Enterprise Linux 10 Via RHSA-2026:72831 https://access.redhat.com/errata/RHSA-2026:72831
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.6 Extended Update Support Via RHSA-2026:72830 https://access.redhat.com/errata/RHSA-2026:72830
This issue has been addressed in the following products: Red Hat Enterprise Linux 9 Via RHSA-2026:72832 https://access.redhat.com/errata/RHSA-2026:72832
This issue has been addressed in the following products: NVIDIA for RHEL 10 Via RHSA-2026:73788 https://access.redhat.com/errata/RHSA-2026:73788