# CVE-2026-99247: tracing: Do not initialize tracefs work if tracing is disabled

CVE-2026-99247 is fixed in linux on 1 platform, first by DEBIAN-CVE-2026-99247, released November 3, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-99247
- Priority: Routine
- CVSS: 4.1 (Moderate)
- EPSS: 0.0016
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Nov 3, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-99247

## Description

In the Linux kernel, the following vulnerability has been resolved:  tracing: Do not initialize tracefs work if tracing is disabled  If trace buffer allocation fails during early boot (e.g.  in early_trace_init() -> allocate_trace_buffers()), tracing_disabled is left set to 1 and the global trace array events list remains uninitialized.  Later during boot, tracer_init_tracefs() (invoked via fs_initcall) queues tracerfs_init_work asynchronously without checking if tracing was disabled.  When tracer_init_tracefs_work_func() runs, it calls event_trace_init() and init_tracer_tracefs(&global_trace, NULL) unconditionally.  This leads to __find_event_file() dereferencing an uninitialized tr->events list, causing an early boot NULL pointer dereference Oops:    BUG: Kernel NULL pointer dereference on read at 0x00000010   Faulting instruction address: 0xc000000000485be0   Oops: Kernel access of bad area, sig: 7 [#1]   ...   NIP [c000000000485be0] __find_event_file+0x70/0x3c0   LR  [c000000000448874] init_tracer_tracefs+0x274/0xc80   Call Trace:    init_tracer_tracefs+0x274/0xc80    tracer_init_tracefs_work_func+0x50/0x320    process_one_work+0x1e8/0x5c0    worker_thread+0x1dc/0x3d0    kthread+0x194/0x1b0    start_kernel_thread+0x14/0x18  Check tracing_disabled at the beginning of tracer_init_tracefs_work_func() and return immediately if tracing is disabled or failed to initialize, preventing the crash.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 13.5 (trixie) | 6.12.115-1 | [DEBIAN-CVE-2026-99247](https://patchblox.com/security/data/fix/linux/debian-cve-2026-99247.md) | Nov 3, 2026 |
| Linux | linux Debian 14 | 7.2.13-1 | [DEBIAN-CVE-2026-99247](https://patchblox.com/security/data/fix/linux/debian-cve-2026-99247.md) | Nov 3, 2026 |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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