CVE-2025-38640
NoneCVSS
—
EPSS
0.2%
Published
Aug 22, 2025
CISA due date
—
Cloudanix analysis
A flaw in the Linux kernel's network filtering code can cause the system to crash when certain network programs run during data transmission.
- Exploitation
- Local Privilege
- Attacker needs
- Low Privilege
- Complexity
- Moderate
- Impact
- Denial Of Service
- Component
- OS kernel
- Class
- Race Condition
- Remediation
- Upgrade
- Effort
- Medium
- Patch risk
- Low
What it actually does
The nf_hook_run_bpf function invokes a BPF program without ensuring migration is disabled on the current CPU, violating the non-migratable context assumption inside __bpf_prog_run and triggering a kernel assertion failure.
Why it matters to the business
Systems may experience unexpected kernel crashes or instability during network transmission under specific traffic patterns, leading to service disruption and requiring restarts or patches.
How an attack unfolds
An attacker sends crafted network traffic that reaches the netfilter hook in the transmit path while a BPF program is attached; the missing migration disablement causes the kernel assertion to fire and panic the system. Related threat actors have targeted similar Linux kernel race conditions for privilege escalation on container-optimized environments.
How to fix it
Update to a kernel containing the fix that replaces the direct bpf_prog_run call with bpf_prog_run_pin_on_cpu inside nf_hook_run_bpf. For affected chromium packages on Debian 12, upgrade to version 138.0.7204.168-1~deb12u1 or later.
How to confirm the fix worked
Confirm the presence of bpf_prog_run_pin_on_cpu in nf_hook_run_bpf via source inspection or binary diff; test that the migration-disabled assertion no longer triggers under the previously failing xmit-path workload.
Typical attack path
- Attach a netfilter BPF program that runs on packet transmit
- Trigger TCP or IP output path from a user-space socket under concurrent scheduling
- Cause the hook to execute without migration disabled
- Trigger the in_atomic / migration_disabled assertion inside the BPF interpreter
How to detect it
Search kernel logs for the exact BUG message 'assuming non migratable context' combined with the call trace through nf_hook_run_bpf and __bpf_prog_run; correlate with sshd-session or other processes performing TCP sendmsg under load.
What your security team should do
- Prioritize kernel updates on all systems exposing netfilter BPF hooks
- Monitor for kernel BUG splats referencing include/linux/filter.h:703
- Limit untrusted BPF program attachment until patches are applied
- Review container runtime configurations for similar race exposures
The record
In the Linux kernel, the following vulnerability has been resolved: bpf: Disable migration in nf_hook_run_bpf(). syzbot reported that the netfilter bpf prog can be called without migration disabled in xmit path. Then the assertion in __bpf_prog_run() fails, triggering the splat below. [0] Let's use bpf_prog_run_pin_on_cpu() in nf_hook_run_bpf(). [0]: BUG: assuming non migratable context at ./include/linux/filter.h:703 in_atomic(): 0, irqs_disabled(): 0, migration_disabled() 0 pid: 5829, name: sshd-session 3 locks held by sshd-session/5829: #0: ffff88807b4e4218 (sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1667 [inline] #0: ffff88807b4e4218 (sk_lock-AF_INET){+.+.}-{0:0}, at: tcp_sendmsg+0x20/0x50 net/ipv4/tcp.c:1395 #1: ffffffff8e5c4e00 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #1: ffffffff8e5c4e00 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #1: ffffffff8e5c4e00 (rcu_read_lock){....}-{1:3}, at: __ip_queue_xmit+0x69/0x26c0 net/ipv4/ip_output.c:470 #2: ffffffff8e5c4e00 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #2: ffffffff8e5c4e00 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #2: ffffffff8e5c4e00 (rcu_read_lock){....}-{1:3}, at: nf_hook+0xb2/0x680 include/linux/netfilter.h:241 CPU: 0 UID: 0 PID: 5829 Comm: sshd-session Not tainted 6.16.0-rc6-syzkaller-00002-g155a3c003e55 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x16c/0x1f0 lib/dump_stack.c:120 __cant_migrate kernel/sched/core.c:8860 [inline] __cant_migrate+0x1c7/0x250 kernel/sched/core.c:8834 __bpf_prog_run include/linux/filter.h:703 [inline] bpf_prog_run include/linux/filter.h:725 [inline] nf_hook_run_bpf+0x83/0x1e0 net/netfilter/nf_bpf_link.c:20 nf_hook_entry_hookfn include/linux/netfilter.h:157 [inline] nf_hook_slow+0xbb/0x200 net/netfilter/core.c:623 nf_hook+0x370/0x680 include/linux/netfilter.h:272 NF_HOOK_COND include/linux/netfilter.h:305 [inline] ip_output+0x1bc/0x2a0 net/ipv4/ip_output.c:433 dst_output include/net/dst.h:459 [inline] ip_local_out net/ipv4/ip_output.c:129 [inline] __ip_queue_xmit+0x1d7d/0x26c0 net/ipv4/ip_output.c:527 __tcp_transmit_skb+0x2686/0x3e90 net/ipv4/tcp_output.c:1479 tcp_transmit_skb net/ipv4/tcp_output.c:1497 [inline] tcp_write_xmit+0x1274/0x84e0 net/ipv4/tcp_output.c:2838 __tcp_push_pending_frames+0xaf/0x390 net/ipv4/tcp_output.c:3021 tcp_push+0x225/0x700 net/ipv4/tcp.c:759 tcp_sendmsg_locked+0x1870/0x42b0 net/ipv4/tcp.c:1359 tcp_sendmsg+0x2e/0x50 net/ipv4/tcp.c:1396 inet_sendmsg+0xb9/0x140 net/ipv4/af_inet.c:851 sock_sendmsg_nosec net/socket.c:712 [inline] __sock_sendmsg net/socket.c:727 [inline] sock_write_iter+0x4aa/0x5b0 net/socket.c:1131 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x6c7/0x1150 fs/read_write.c:686 ksys_write+0x1f8/0x250 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fe7d365d407 Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff RSP:
Affected packages
| Ecosystem | Package | Introduced | Fixed |
|---|---|---|---|
| Debian:13 | linux | 0 | No fix |
| Debian:14 | linux | 0 | No fix |
| Debian:14 | linux | 0 | 6.16.3-1 |
| Linux | Kernel | 6.4.0 | 6.6.102 |
| Mageia:9 | kernel | 0 | 6.6.105-1.mga9 |
| Mageia:9 | kernel-linus | 0 | 6.6.105-1.mga9 |
| Mageia:9 | kmod-virtualbox | 0 | 7.1.10-10.mga9 |
| Mageia:9 | kmod-xtables-addons | 0 | 3.24-86.mga9 |
| Mageia:9 | mageia-repos | 0 | 9-4.mga9 |
| Mageia:9 | meta-task | 0 | 9-4.mga9 |
| SUSE:Linux Enterprise High Availability Extension 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.73.1 |
| SUSE:Linux Enterprise Live Patching 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.73.1 |
| SUSE:Linux Enterprise Live Patching 15 SP6 | kernel-livepatch-SLE15-SP6-RT_Update_16 | 0 | 1-150600.1.3.1 |
| SUSE:Linux Enterprise Live Patching 15 SP6 | kernel-livepatch-SLE15-SP6_Update_16 | 0 | 1-150600.13.3.1 |
| SUSE:Linux Enterprise Live Patching 15 SP7 | kernel-livepatch-SLE15-SP7-RT_Update_5 | 0 | 1-150700.1.3.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP6 | kernel-64kb | 0 | 6.4.0-150600.23.73.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.73.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP6 | kernel-default-base | 0 | 6.4.0-150600.23.73.1.150600.12.32.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP6 | kernel-source | 0 | 6.4.0-150600.23.73.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP6 | kernel-zfcpdump | 0 | 6.4.0-150600.23.73.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP6 | kernel-docs | 0 | 6.4.0-150600.23.73.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP6 | kernel-obs-build | 0 | 6.4.0-150600.23.73.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP6 | kernel-source | 0 | 6.4.0-150600.23.73.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP6 | kernel-syms | 0 | 6.4.0-150600.23.73.1 |
| SUSE:Linux Enterprise Module for Legacy 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.73.1 |
| SUSE:Linux Enterprise Module for Public Cloud 15 SP6 | kernel-azure | 0 | 6.4.0-150600.8.52.1 |
| SUSE:Linux Enterprise Module for Public Cloud 15 SP6 | kernel-source-azure | 0 | 6.4.0-150600.8.52.1 |
| SUSE:Linux Enterprise Module for Public Cloud 15 SP6 | kernel-syms-azure | 0 | 6.4.0-150600.8.52.1 |
| SUSE:Linux Enterprise Workstation Extension 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.73.1 |
| SUSE:Real Time Module 15 SP6 | kernel-rt | 0 | 6.4.0-150600.10.55.1 |
| SUSE:Real Time Module 15 SP6 | kernel-rt_debug | 0 | 6.4.0-150600.10.55.1 |
| SUSE:Real Time Module 15 SP6 | kernel-source-rt | 0 | 6.4.0-150600.10.55.1 |
| SUSE:Real Time Module 15 SP6 | kernel-syms-rt | 0 | 6.4.0-150600.10.55.1 |
| SUSE:Real Time Module 15 SP7 | kernel-rt | 0 | 6.4.0-150700.7.19.1 |
| SUSE:Real Time Module 15 SP7 | kernel-source-rt | 0 | 6.4.0-150700.7.19.1 |
| SUSE:Real Time Module 15 SP7 | kernel-syms-rt | 0 | 6.4.0-150700.7.19.1 |
| openSUSE:Leap 15.6 | dtb-aarch64 | 0 | 6.4.0-150600.23.73.1 |
| openSUSE:Leap 15.6 | kernel-64kb | 0 | 6.4.0-150600.23.73.1 |
| openSUSE:Leap 15.6 | kernel-azure | 0 | 6.4.0-150600.8.52.1 |
| openSUSE:Leap 15.6 | kernel-debug | 0 | 6.4.0-150600.23.73.1 |
| openSUSE:Leap 15.6 | kernel-default | 0 | 6.4.0-150600.23.73.1 |
| openSUSE:Leap 15.6 | kernel-default-base | 0 | 6.4.0-150600.23.73.1.150600.12.32.1 |
| openSUSE:Leap 15.6 | kernel-docs | 0 | 6.4.0-150600.23.73.1 |
| openSUSE:Leap 15.6 | kernel-kvmsmall | 0 | 6.4.0-150600.23.73.1 |
| openSUSE:Leap 15.6 | kernel-obs-build | 0 | 6.4.0-150600.23.73.1 |
| openSUSE:Leap 15.6 | kernel-obs-qa | 0 | 6.4.0-150600.23.73.1 |
| openSUSE:Leap 15.6 | kernel-rt | 0 | 6.4.0-150600.10.55.1 |
| openSUSE:Leap 15.6 | kernel-rt_debug | 0 | 6.4.0-150600.10.55.1 |
| openSUSE:Leap 15.6 | kernel-source | 0 | 6.4.0-150600.23.73.1 |
| openSUSE:Leap 15.6 | kernel-source-azure | 0 | 6.4.0-150600.8.52.1 |
| openSUSE:Leap 15.6 | kernel-source-rt | 0 | 6.4.0-150600.10.55.1 |
| openSUSE:Leap 15.6 | kernel-syms | 0 | 6.4.0-150600.23.73.1 |
| openSUSE:Leap 15.6 | kernel-syms-azure | 0 | 6.4.0-150600.8.52.1 |
| openSUSE:Leap 15.6 | kernel-syms-rt | 0 | 6.4.0-150600.10.55.1 |
| openSUSE:Leap 15.6 | kernel-zfcpdump | 0 | 6.4.0-150600.23.73.1 |
| openSUSE:Leap 16.0 | dtb-aarch64 | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-64kb | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-default | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-default-base | 0 | 6.12.0-160000.6.1.160000.2.4 |
| openSUSE:Leap 16.0 | kernel-docs | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-kvmsmall | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-obs-build | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-obs-qa | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-rt | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-source | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-syms | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-zfcpdump | 0 | 6.12.0-160000.6.1 |
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