In the Linux kernel, the following vulnerability has been resolved:
bpf: Disable preemption in bpf_event_output
We received report [1] of kernel crash, which is caused by using nesting protection without disabled preemption.
The bpf_event_output can be called by programs executed by bpf_prog_run_array_cg function that disabled migration but keeps preemption enabled.
This can cause task to be preempted by another one inside the nesting protection and lead eventually to two tasks using same perf_sample_data buffer and cause crashes like:
BUG: kernel NULL pointer dereference, address: 0000000000000001 #PF: supervisor instruction fetch in kernel mode #PF: error_code(0x0010) - not-present page ... ? perf_output_sample+0x12a/0x9a0 ? finish_task_switch.isra.0+0x81/0x280 ? perf_event_output+0x66/0xa0 ? bpf_event_output+0x13a/0x190 ? bpf_event_output_data+0x22/0x40 ? bpf_prog_dfc84bbde731b257_cil_sock4_connect+0x40a/0xacb ? xa_load+0x87/0xe0 ? __cgroup_bpf_run_filter_sock_addr+0xc1/0x1a0 ? release_sock+0x3e/0x90 ? sk_setsockopt+0x1a1/0x12f0 ? udp_pre_connect+0x36/0x50 ? inet_dgram_connect+0x93/0xa0 ? __sys_connect+0xb4/0xe0 ? udp_setsockopt+0x27/0x40 ? __pfx_udp_push_pending_frames+0x10/0x10 ? __sys_setsockopt+0xdf/0x1a0 ? __x64_sys_connect+0xf/0x20 ? do_syscall_64+0x3a/0x90 ? entry_SYSCALL_64_after_hwframe+0x72/0xdc
Fixing this by disabling preemption in bpf_event_output.
[1] https://github.com/cilium/cilium/issues/26756
CVSS Details
- CVSS 3.1 Base Score: 7.8
- CVSS 3.1 Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon Linux Ami 2 | — | Upgrade kernel-debuginfo-common-aarch64Upgrade kernel-develUpgrade python-perfUpgrade kernelUpgrade kernel-livepatch-5.10.192-182.736Upgrade kernel-debuginfo-common-x86_64Upgrade kernel-toolsUpgrade bpftoolUpgrade bpftool-debuginfoUpgrade kernel-tools-develUpgrade kernel-tools-debuginfoUpgrade python-perf-debuginfoUpgrade perfUpgrade kernel-debuginfoUpgrade perf-debuginfoUpgrade kernel-headersUpgrade kernel-livepatch-5.15.128-80.144 | May 20, 2026 | May 20, 2026 |
| Amazon_linux_2023 | — | Upgrade kernel-develUpgrade kernel-libbpf-staticUpgrade kernel-tools-develUpgrade kernel-debuginfo-common-x86_64Upgrade kernelUpgrade python3-perfUpgrade kernel-libbpf-develUpgrade python3-perf-debuginfoUpgrade bpftoolUpgrade perf-debuginfoUpgrade kernel-tools-debuginfoUpgrade kernel-livepatch-6.1.49-69.116Upgrade kernel-headersUpgrade perfUpgrade kernel-toolsUpgrade kernel-debuginfoUpgrade kernel-libbpfUpgrade kernel-debuginfo-common-aarch64Upgrade bpftool-debuginfo | Feb 20, 2026 | Dec 30, 2025 |
| Debian | — | Upgrade linux | Dec 31, 2025 | Dec 31, 2025 |
| Redhat_linux | — | No solution exists | Jul 17, 2026 | Dec 30, 2025 |
| Ubuntu | — | Upgrade linux-azureUpgrade linux-hwe-5.15Upgrade linux-azure-fdeUpgrade linuxUpgrade linux-lowlatency-hwe-5.15Upgrade linux-intel-iotg-5.15Upgrade linux-awsUpgrade linux-lowlatencyUpgrade linux-gcp-5.15Upgrade linux-ibmUpgrade linux-azure-5.15Upgrade linux-realtimeUpgrade linux-raspiUpgrade linux-intel-iotgUpgrade linux-gkeUpgrade linux-gkeopUpgrade linux-nvidia-tegraUpgrade linux-nvidia-tegra-5.15Upgrade linux-ibm-5.15Upgrade linux-kvmUpgrade linux-oracle-5.15Upgrade linux-nvidia-tegra-igxUpgrade linux-xilinx-zynqmpUpgrade linux-nvidiaUpgrade linux-oracleUpgrade linux-intel-iot-realtimeUpgrade linux-bluefieldUpgrade linux-riscv-5.15Upgrade linux-gcpUpgrade linux-aws-5.15 | Jan 6, 2026 | Jan 2, 2026 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | May 27, 2026 | Dec 30, 2025 |
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