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CVE-2026-74275
cxl/region: Fix out-of-bounds access in cxl_cancel_auto_attach()
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem drivers/cxl. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-74275 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 | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | not affected | 6.12.113-1 | Nothing to do. trixie never shipped the vulnerable code. |
| 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
In cxl_cancel_auto_attach(), it assumes cxled->pos is a valid index for accessing p->targets[]. However, cxled->pos can be set to negative errno in cxl_region_sort_targets() if cxl_calc_interleave_pos() fails. This causes the driver to use a negative index to access p->targets[], resulting in out-of-bounds access. Fix it by walking p->targets[] instead of using cxled->pos directly.
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.
drivers/cxl/core/region.c
- What this is
- COMPUTE EXPRESS LINK (CXL)MAINTAINERS section matched on drivers/cxl/ · linux-cxl@vger.kernel.org · Maintained
Check it on the machine
grep -wE 'CONFIG_CXL_BUS|CONFIG_CXL_REGION' /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 armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, i386/686, i386/686-pae, i386/rt/686-pae
- trixieYnot built on armel/rpi, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, s390x/s390x
- forky, sidYnot built on armhf/armmp, armhf/armmp-lpae, loong64/loong64, s390x/s390x
- Y
- built in where it is built at all; some flavours do not build it
- Build switches
- CONFIG_CXL_BUS, CONFIG_CXL_REGION
- 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
- 8.4 high
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.18%, higher than 7.0% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- drivers/cxl
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 7.1 | 7.1.5 | 44b2397eb67b |
| 7.1 | 7.2 | cbda6a2c2bec |
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 flaw is in the CXL region driver reached via local kernel paths—CXL endpoint decoder auto-discovery/attach, sysfs region/target management under /sys/bus/cxl/, and PCI/CXL device removal—not via any network protocol or remote packet handler.
- AC:LAttack complexity, low
- Once CXL auto-region assembly fails in cxl_region_sort_targets() leaving a decoder AUTO_STAGED with a negative cxled->pos, an attacker who can present or remove CXL endpoints can reliably trigger cxl_cancel_auto_attach() during decoder teardown without uncontrollable timing or memory-layout dependencies.
- PR:NPrivileges required, none
- The vulnerable teardown path runs automatically during kernel-driven CXL endpoint decoder unregistration after failed auto-assembly; it does not require authenticated access or elevated credentials, only that a CXL topology causes cxl_calc_interleave_pos() to fail before the decoder is removed.
- UI:NUser interaction, none
- Exploitation requires no end-user interaction such as opening files or mounting filesystems; it is triggered by kernel CXL auto-discovery, region assembly failure, and subsequent endpoint decoder detach/unregister events.
- S:UScope, unchanged
- The out-of-bounds access corrupts kernel cxl_region_params memory within the same kernel security boundary and does not by itself cross VM, container, or IOMMU isolation boundaries.
- C:HConfidentiality impact, high
- cxl_region_by_target() performs an out-of-bounds read using the negative cxled->pos as an index into p->targets[], leaking adjacent kernel memory from the cxl_region_params structure before the array base.
- I:HIntegrity impact, high
- cxl_cancel_auto_attach() writes NULL via p->targets[pos] using the same negative index, corrupting adjacent fields such as the region resource pointer and other cxl_region_params metadata exploitable for further memory corruption.
- A:HAvailability impact, high
- Out-of-bounds access and corruption of critical region metadata pointers can cause kernel oops, panic, or hang during CXL region teardown on systems with CONFIG_CXL_REGION and interleaved CXL memory expanders.