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Linux KernelOperating system · Linux

CVE-2026-23088

MEDIUM · 5.5 CVSS v3.1 Published 2026-02-04
Fix available
A fix is available. Upgrade to 5.11 / 5.16 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: tracing: Fix crash on synthetic stacktrace field usage When creating a synthetic event based on an existing synthetic event that had a stacktrace field and the new synthetic event used that field a kernel crash occurred: ~# cd /sys/kernel/tracing ~# echo 's:stack unsigned long stack[];' > dynamic_events ~# echo 'hist:keys=prev_pid:s0=common_stacktrace if prev_state & 3' >> events/sched/sched_switch/trigger ~# echo 'hist:keys=next_pid:s1=$s0:onmatch(sched.sched_switch).trace(stack,$s1)' >> events/sched/sched_switch/trigger The above creates a synthetic event that takes a stacktrace when a task schedules out in a non-running state and passes that stacktrace to the sched_switch event when that task schedules back in. It triggers the "stack" synthetic event that has a stacktrace as its field (called "stack"). ~# echo 's:syscall_stack s64 id; unsigned long stack[];' >> dynamic_events ~# echo 'hist:keys=common_pid:s2=stack' >> events/synthetic/stack/trigger ~# echo 'hist:keys=common_pid:s3=$s2,i0=id:onmatch(synthetic.stack).trace(syscall_stack,$i0,$s3)' >> events/raw_syscalls/sys_exit/trigger The above makes another synthetic event called "syscall_stack" that attaches the first synthetic event (stack) to the sys_exit trace event and records the stacktrace from the stack event with the id of the system call that is exiting. When enabling this event (or using it in a historgram): ~# echo 1 > events/synthetic/syscall_stack/enable Produces a kernel crash! BUG: unable to handle page fault for address: 0000000000400010 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: Oops: 0000 [#1] SMP PTI CPU: 6 UID: 0 PID: 1257 Comm: bash Not tainted 6.16.3+deb14-amd64 #1 PREEMPT(lazy) Debian 6.16.3-1 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.17.0-debian-1.17.0-1 04/01/2014 RIP: 0010:trace_event_raw_event_synth+0x90/0x380 Code: c5 00 00 00 00 85 d2 0f 84 e1 00 00 00 31 db eb 34 0f 1f 00 66 66 2e 0f 1f 84 00 00 00 00 00 66 66 2e 0f 1f 84 00 00 00 00 00 <49> 8b 04 24 48 83 c3 01 8d 0c c5 08 00 00 00 01 cd 41 3b 5d 40 0f RSP: 0018:ffffd2670388f958 EFLAGS: 00010202 RAX: ffff8ba1065cc100 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000001 RSI: fffff266ffda7b90 RDI: ffffd2670388f9b0 RBP: 0000000000000010 R08: ffff8ba104e76000 R09: ffffd2670388fa50 R10: ffff8ba102dd42e0 R11: ffffffff9a908970 R12: 0000000000400010 R13: ffff8ba10a246400 R14: ffff8ba10a710220 R15: fffff266ffda7b90 FS: 00007fa3bc63f740(0000) GS:ffff8ba2e0f48000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000400010 CR3: 0000000107f9e003 CR4: 0000000000172ef0 Call Trace: <TASK> ? __tracing_map_insert+0x208/0x3a0 action_trace+0x67/0x70 event_hist_trigger+0x633/0x6d0 event_triggers_call+0x82/0x130 trace_event_buffer_commit+0x19d/0x250 trace_event_raw_event_sys_exit+0x62/0xb0 syscall_exit_work+0x9d/0x140 do_syscall_64+0x20a/0x2f0 ? trace_event_raw_event_sched_switch+0x12b/0x170 ? save_fpregs_to_fpstate+0x3e/0x90 ? _raw_spin_unlock+0xe/0x30 ? finish_task_switch.isra.0+0x97/0x2c0 ? __rseq_handle_notify_resume+0xad/0x4c0 ? __schedule+0x4b8/0xd00 ? restore_fpregs_from_fpstate+0x3c/0x90 ? switch_fpu_return+0x5b/0xe0 ? do_syscall_64+0x1ef/0x2f0 ? do_fault+0x2e9/0x540 ? __handle_mm_fault+0x7d1/0xf70 ? count_memcg_events+0x167/0x1d0 ? handle_mm_fault+0x1d7/0x2e0 ? do_user_addr_fault+0x2c3/0x7f0 entry_SYSCALL_64_after_hwframe+0x76/0x7e The reason is that the stacktrace field is not labeled as such, and is treated as a normal field and not as a dynamic event that it is. In trace_event_raw_event_synth() the event is field is still treated as a dynamic array, but the retrieval of the data is considered a normal field, and the reference is just the meta data: // Meta data is retrieved instead of a dynamic array ---truncated---

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-476

The code follows a pointer that is null, crashing the process. An attacker who can reliably trigger it turns the crash into a denial of service. The fix is checking for null before use and handling the failure path gracefully.

General guidance for the null pointer dereference class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 5.10.237, < 5.11>= 5.15.124, < 5.16>= 6.1.43, < 6.2>= 6.3, < 6.6.122>= 6.7, < 6.12.68>= 6.13, < 6.18.8= 6.19

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 5.11 / 5.16 / 6.2 or later
Fixed in 5.115.166.2
Vendor patch git.kernel.org →
Recommended fix High confidence

Upgrade to kernel 5.11.x, 5.16.x, 6.2.x, or 6.6.122 or later depending on your current branch. For example, if running 6.1.x, upgrade to 6.2.x or later. If running 6.3-6.6.x, upgrade to 6.6.122 or later.

  1. Identify the currently running kernel version using 'uname -r'
  2. Download or obtain the kernel source or prebuilt packages for a fixed version
  3. Apply the upstream stable patch commit 327af07dff6ab5650b21491eb4f69694999ff3d1 to the kernel source if building custom kernel
  4. Alternatively, upgrade to a kernel version that includes this fix (see upgrade_path)
  5. Reboot the system to load the patched kernel
  6. Verify the fix by testing synthetic event creation with stacktrace fields as described in the CVE description
Caveat Kernel upgrades may require rebuilding out-of-tree modules and could introduce regressions in other drivers. Ensure compatibility with user-space tracing tools.

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $2,850. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

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