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CVE-2026-72012
tracing/osnoise: Call synchronize_rcu() when unregistering
Published 2026-08-15 (2 months 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-2026-72012 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 | fixedDLA-4777-1 · 2026-09-08 · text | 6.1.187-1 | Update the kernel and reboot. DLA-4777-1 shipped the fix on 2026-09-08, in 6.1.187-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.100-1 | Update the kernel and reboot. Fixed in 6.12.100-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
This ensures that any RCU readers traversing the instance list have finished, before releasing the reference on the tracer that the instance points to.
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_osnoise.c
- What this is
- TRACING OS NOISE / LATENCY TRACERSMAINTAINERS section matched on kernel/trace/trace_osnoise.c · Maintained
Check it on the machine
grep -wE 'CONFIG_FUNCTION_TRACER|CONFIG_OSNOISE_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 amd64/amd64, amd64/cloud-amd64, arm64/arm64, arm64/cloud-arm64, arm64/rt/arm64, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, i386/686, i386/686-pae, ppc64el/powerpc64le
- trixieYnot built on amd64/amd64, amd64/cloud-amd64, arm64/arm64, arm64/arm64-16k, arm64/cloud-arm64, arm64/rt/arm64, armel/rpi, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
- forky, sidYnot built on amd64/amd64, amd64/cloud-amd64, arm64/arm64, arm64/arm64-16k, arm64/cloud-arm64, arm64/rt-arm64, armhf/armmp, armhf/armmp-lpae, loong64/loong64, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
- Y
- built in where it is built at all; some flavours do not build it
- Build switches
- CONFIG_FUNCTION_TRACER, CONFIG_OSNOISE_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
- 2026-08-15 (2 months 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
- 0.16%, higher than 5.3% 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 |
|---|---|---|
| 5.17 | 6.1.184 | 428cedade9b2 |
| 5.17 | 6.6.145 | 3c693635bb7b |
| 5.17 | 6.12.97 | 38366140dc8e |
| 5.17 | 6.18.40 | fad36954b295 |
| 5.17 | 7.1.5 | dd0160a08423 |
| 5.17 | 7.2 | fe58f457ad8d |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4777-1 | 2026-09-08 | bookworm 6.1.187-1 | 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
- Exploitation requires writing tracefs (e.g. enabling osnoise/timerlat via current_tracer and deleting a tracing instance); there is no network, adjacent, or physical entry path to osnoise_unregister_instance().
- AC:LAttack complexity, low
- An attacker who can configure tracing controls both teardown and sampling; deleting a trace instance while osnoise/timerlat is active races RCU readers that still dereference inst->tr, and this race is reliably attacker-driven.
- PR:LPrivileges required, low
- Triggering requires tracefs write access to configure/destroy tracing instances; this is not init-namespace root on every system (tracing group/remounted tracefs or CAP_SYS_ADMIN in a container with tracefs mounted suffices).
- UI:NUser interaction, none
- No victim interaction is required; exploitation is achieved entirely by the attacker's tracing configuration and concurrent instance teardown.
- S:UScope, unchanged
- The use-after-free corrupts kernel memory within the same kernel security domain; it does not cross VM, IOMMU, or sandbox boundaries by itself.
- C:HConfidentiality impact, high
- Deferred kvfree_rcu_mightsleep() lets __remove_instance() free the trace_array while RCU readers in IRQ/NMI/timerlat paths still dereference inst->tr, a classic UAF enabling arbitrary kernel memory disclosure.
- I:HIntegrity impact, high
- The dangling trace_array pointer can be leveraged for heap corruption and control-flow hijack; UAF of kernel heap objects is scored as high integrity impact even when the immediate failure mode is a crash.
- A:HAvailability impact, high
- Concurrent access to a freed trace_array causes kernel oops/panic from RCU list walkers and buffer operations; UAF in interrupt context can crash or hang the system even without full exploitation.