In the Linux kernel, the following vulnerability has been resolved:
ipv6: fix a BUG in rt6_get_pcpu_route() under PREEMPT_RT
On PREEMPT_RT kernels, after rt6_get_pcpu_route() returns NULL, the current task can be preempted. Another task running on the same CPU may then execute rt6_make_pcpu_route() and successfully install a pcpu_rt entry. When the first task resumes execution, its cmpxchg() in rt6_make_pcpu_route() will fail because rt6i_pcpu is no longer NULL, triggering the BUG_ON(prev). It's easy to reproduce it by adding mdelay() after rt6_get_pcpu_route().
Using preempt_disable/enable is not appropriate here because ip6_rt_pcpu_alloc() may sleep.
Fix this by handling the cmpxchg() failure gracefully on PREEMPT_RT: free our allocation and return the existing pcpu_rt installed by another task. The BUG_ON is replaced by WARN_ON_ONCE for non-PREEMPT_RT kernels where such races should not occur.
CVSS Details
- CVSS 3.1 Base Score: 7.5
- CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon_linux_2023 | — | Upgrade kernel6.12-libbpfUpgrade kernel6.12-modules-extra-commonUpgrade kernel6.12-tools-debuginfoUpgrade kernel6.12-toolsUpgrade kernel6.12-libbpf-staticUpgrade python3-perf6.12-debuginfoUpgrade perf6.12-debuginfoUpgrade kernel6.12-debuginfo-common-aarch64Upgrade kernel6.12-modules-extraUpgrade python3-perf6.12Upgrade kernel6.12-debuginfo-common-x86_64Upgrade kernel6.12-debuginfoUpgrade kernel6.12-tools-develUpgrade kernel6.12-develUpgrade kernel-livepatch-6.12.64-87.122Upgrade bpftool6.12-debuginfoUpgrade kernel6.12-libbpf-debuginfoUpgrade bpftool6.12Upgrade kernel6.12-libbpf-develUpgrade kernel6.12-headersUpgrade kernel6.12Upgrade perf6.12 | Feb 20, 2026 | Jan 13, 2026 |
| Debian | — | Upgrade linux | Jul 23, 2026 | Jul 23, 2026 |
| Oracle_linux | — | Upgrade kernel-uek | Feb 24, 2026 | Jan 13, 2026 |
| Redhat_linux | — | No solution exists | Jul 17, 2026 | Jan 13, 2026 |
| Ubuntu | — | Upgrade linux-image-generic-64k-6.17Upgrade linux-image-realtime-5.15Upgrade linux-image-nvidia-tegra-rt-6.8Upgrade linux-image-nvidia-tegra-igxUpgrade linux-image-6.17.0-1010-realtimeUpgrade linux-image-5.15.0-1046-nvidia-tegra-igx-rtUpgrade linux-image-6.8.1-1047-realtimeUpgrade linux-image-realtimeUpgrade linux-image-6.17.0-22-generic-64kUpgrade linux-image-realtime-6.17Upgrade linux-image-5.15.0-1057-nvidia-tegra-rtUpgrade linux-image-virtualUpgrade linux-image-realtime-6.8.1Upgrade linux-image-5.15.0-1104-realtimeUpgrade linux-image-nvidia-tegra-igx-rtUpgrade linux-image-raspi-realtimeUpgrade linux-image-nvidia-tegra-rt-5.15Upgrade linux-image-nvidia-tegra-5.15Upgrade linux-image-realtime-hwe-22.04Upgrade linux-image-5.15.0-1097-intel-iot-realtimeUpgrade linux-image-nvidia-tegra-rtUpgrade linux-image-5.15.0-1057-nvidia-tegraUpgrade linux-image-6.8.0-1022-nvidia-tegraUpgrade linux-image-realtime-hwe-24.04Upgrade linux-image-generic-64kUpgrade linux-image-nvidia-tegra-igx-rt-5.15Upgrade linux-image-nvidia-tegra-igx-5.15Upgrade linux-image-intel-iot-realtimeUpgrade linux-image-5.15.0-1046-nvidia-tegra-igxUpgrade linux-image-genericUpgrade linux-image-raspi-realtime-6.8Upgrade linux-image-nvidia-tegraUpgrade linux-image-intel-iot-realtime-5.15Upgrade linux-image-6.17.0-22-genericUpgrade linux-image-generic-6.17Upgrade linux-image-6.8.0-1022-nvidia-tegra-rtUpgrade linux-image-6.8.0-2042-raspi-realtimeUpgrade linux-image-nvidia-tegra-6.8Upgrade linux-image-virtual-6.17 | Apr 10, 2026 | Jan 13, 2026 |
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