High [CVE-2026-74581] use-after-free in fib6_rule_suppress due to stale res->rt6 pointer
This high-severity Red Hat Linux advisory covers CVE-2026-74581 affecting NVIDIA for RHEL 10, Red Hat Enterprise Linux 10.0 Extended Update Support, Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support.
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Summary
In the Linux kernel, the following vulnerability has been resolved: net: ipv6: clear suppressed fib6 rule result fib6_rule_suppress() drops a suppressed route with ip6_rt_put_flags(), but leaves res->rt6 pointing at the released rt6_info. If no later rule supplies a replacement, fib6_rule_lookup() still sees res.rt6 and returns that stale dst to its caller.
A suppressing rule can therefore leak a released route back to rt6_lookup(), and the next put hits rcuref_put_slowpath() from dst_release(). Clear res->rt6 when suppressing the route so suppressed lookups fall through to the null dst instead of reusing the released one.
A use-after-free vulnerability was found in the Linux kernel's IPv6 FIB rule lookup path. 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. Red Hat severity: Important — CVSS 7.8 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).
Weakness: CWE-416.
Affected products named by the advisory: NVIDIA for RHEL 10; Red Hat Enterprise Linux 10.0 Extended Update Support; Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support; Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On; and 8 more.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 13 days ago·verify at source
- kernel-0:6.12.0-231.20.el10nv
- kernel-0:6.12.0-211.51.1.el10_2
- kernel-0:6.12.0-55.102.1.el10_0
- kernel-rt-0:4.18.0-553.159.1.rt7.500.el8_10
- kernel-0:4.18.0-553.159.1.el8_10
- kernel-0:4.18.0-305.202.1.el8_4
- kernel-0:4.18.0-372.209.1.el8_6
- kernel-0:4.18.0-477.163.1.el8_8
- kernel-0:5.14.0-687.42.1.el9_8
- kernel-0:5.14.0-284.189.1.el9_2
- kernel-rt-0:5.14.0-284.189.1.rt14.474.el9_2
- kernel-0:5.14.0-427.147.1.el9_4
- kernel-0:5.14.0-570.136.1.el9_6
- RHSA-2026:72059
- RHSA-2026:63128
- RHSA-2026:62609
- RHSA-2026:63013
- RHSA-2026:63014
- RHSA-2026:59994
- RHSA-2026:60485
- RHSA-2026:61932
- RHSA-2026:59723
- RHSA-2026:60437
- RHSA-2026:60438
- RHSA-2026:60484
- RHSA-2026:60486
Official advisory · high-confidence parse· fetched 13 days ago·verify at source
Mitigation checklist
- To mitigate this issue, disable the `ipv6` kernel module at boot using the kernel command-line parameter: ``` grubby --update-kernel=ALL --args="ipv6.disable=1" ``` A reboot is required for this change to take effect. To verify after reboot: ``` cat /proc/cmdline | grep -o ipv6.disable=1 sysctl net.ipv6.conf.all.disable_ipv6 ``` Applications or services that rely on the IPv6 protocol cannot use this mitigation and should prioritize applying the fix.
Official advisory · high-confidence parse· fetched 13 days ago·verify at source
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