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CVE-2026-90013
tracing: Take trace_array reference when opening options file
Published 2026-09-16 (33 days ago) by the Linux kernel CNA. Subsystem kernel/trace. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-90013 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | vulnerable | 6.1.190-1 | No fix published anywhere yet, neither in Debian nor upstream for the series bookworm tracks. Watch the Debian tracker page for this CVE. Advisories for bookworm have historically landed a median of 23 days after publication. |
| Debian 13trixie | fixedDSA-6568-1 · 2026-10-16 · text | 6.12.113-1 | Update the kernel and reboot. DSA-6568-1 shipped the fix on 2026-10-16, in 6.12.113-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
The options files do not take the trace_array reference for the options they represent. This could cause a use-after-free kernel crash if one of these files is opened by one task and another task removes the instance that the option is for. Because it doesn't take a reference upon opening, it will not stop the removal which will free the options descriptor that is being used. As the options are somewhat dynamic in their creation at boot up, each file represents a flag in the trace_array. The trace_array has an array of indexes to represent each of these flags that is stored in the trace_flags_index array. The address of the index array element is used to pass to the inode->i_private pointer. Then that element is read which holds the index (which represents the flag) and then the index is used to calculate the trace_array descriptor from its trace_flags_index array. One issue is that the index element can not be referenced until the trace_array's reference is taken. To handle this, create a new helper function called: trace_array_options_get() that will iterate all the existing trace_arrays in the ftrace_trace_arrays list (under the trace_types_lock), and compare the passed in address of the index element with the entire array of the trace_array's trace_flags_index array. If it matches, then up the corresponding trace_array's reference and return.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
kernel/trace/trace.c
- What this is
- TRACINGMAINTAINERS section matched on kernel/trace/ · linux-kernel@vger.kernel.org · Maintained
Check it on the machine
grep -wE 'CONFIG_FUNCTION_TRACER|CONFIG_RETHOOK|CONFIG_RING_BUFFER|CONFIG_TRACEPOINTS|CONFIG_TRACE_CLOCK|CONFIG_TRACING' /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
Show whether Debian builds this, per release
Debian builds this, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed.
- bookwormYnot built on arm64/arm64, arm64/cloud-arm64, arm64/rt/arm64, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, ppc64el/powerpc64le
- trixieYnot built on arm64/arm64, arm64/arm64-16k, arm64/cloud-arm64, arm64/rt/arm64, armel/rpi, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp
- forky, sidYnot built on arm64/arm64, arm64/arm64-16k, arm64/cloud-arm64, arm64/rt-arm64, armhf/armmp, armhf/armmp-lpae
- Y
- built in where it is built at all; some flavours do not build it
- Build switches
- CONFIG_FUNCTION_TRACER, CONFIG_RETHOOK, CONFIG_RING_BUFFER, CONFIG_TRACEPOINTS, CONFIG_TRACE_CLOCK, CONFIG_TRACING
- Reads as
- all on means the file is compiled; any one off means it is not.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-09-16 (33 days ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.17%, higher than 6.0% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- kernel/trace
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 2.6.30 | 6.12.112 | 97ceaffbd672 |
| 2.6.30 | 6.18.52 | d0f37d77b9b4 |
| 2.6.30 | 7.2.5 | 64a41f4a9a96 |
| 2.6.30 | 7.3 | f2951ebd15c3 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DSA-6568-1 | 2026-10-16 | trixie 6.12.113-1 | tracker |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:LAttack vector, local
- The UAF is reached only via local tracefs: open() of an instance options file (tracing_open_generic -> trace_options_core_read/write) then rmdir of that instance (__remove_instance). No network, adjacent-radio, or physical-device path reaches get_tr_index() or the freed trace_array.
- AC:LAttack complexity, low
- The attacker fully controls both sides: open an instance options file (no trace_array ref), rmdir the instance so __remove_instance kfree()s the trace_array, then read/write the still-open fd. That sequence is deterministic and retryable; CONFIG_TRACING with instances is standard, not a rare config.
- PR:LPrivileges required, low
- tracing_open_generic() and instance mkdir/rmdir enforce only LOCKDOWN_TRACEFS and DAC (options 0640, dirs 0750) with no capable() gate. Android/Perfetto, ChromeOS, and gid=/uid= tracing mounts routinely delegate this to unprivileged tracing accounts, matching CVE-2026-74606 and CVE-2026-89747.
- UI:NUser interaction, none
- The attacker mkdir()s their own tracing instance, opens options, rmdir()s the instance, and reads or writes the fd themselves. No victim mount, click, or cooperating process is required.
- S:UScope, unchanged
- The use-after-free corrupts a kernel trace_array in the tracing subsystem on the same host. It can yield local privilege escalation but does not cross a VM, IOMMU, or other security authority.
- C:HConfidentiality impact, high
- After rmdir, get_tr_index() reads the freed trace_flags_index byte and reconstructs a trace_array, then trace_options_core_read() loads tr->trace_flags. Reclaiming that slab lets the attacker control the object and obtain an arbitrary kernel read, which kernel CNA guidance scores High for UAF.
- I:HIntegrity impact, high
- trace_options_core_write() calls set_tracer_flag() on the freed/reused trace_array, including tr->current_trace->flag_changed and writes to tr->trace_flags and related tracing state. Heap spraying that object yields an arbitrary kernel write and control-flow hijack primitive.
- A:HAvailability impact, high
- Dereferencing the kfree()d trace_array in get_tr_index()/trace_options_core_read() oopses or panics the kernel, which the fix describes as a use-after-free kernel crash. The attacker can retrigger that crash at will.