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CVE-2026-53187
RDMA/core: Validate cpu_id against nr_cpu_ids in DMAH alloc
Published 2026-06-25 (4 months ago) by the Linux kernel CNA. Subsystem drivers/infiniband. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-53187 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 | 7.0.13-1 | Update the kernel and reboot. Fixed in 7.0.13-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.13-1 | Update the kernel and reboot. Fixed in 7.0.13-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
The cpu_id attribute supplied by user space through UVERBS_ATTR_ALLOC_DMAH_CPU_ID is passed directly to cpumask_test_cpu() without first verifying that the value is within the valid CPU range. Passing such untrusted data to cpumask_test_cpu() may lead to an out-of-bounds read of the underlying cpumask bitmap: the helper expands to a test_bit() that indexes the bitmap by cpu_id / BITS_PER_LONG with no bound check. In addition, on kernels built with CONFIG_DEBUG_PER_CPU_MAPS it trips the WARN_ON_ONCE() in cpumask_check(); combined with panic_on_warn this turns a bad user input into a machine reboot. Reject any cpu_id that is not smaller than nr_cpu_ids with -EINVAL before it is used. Reported by Smatch.
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/infiniband/core/uverbs_std_types_dmah.c
- What this is
- INFINIBAND SUBSYSTEMMAINTAINERS section matched on drivers/infiniband/ · linux-rdma@vger.kernel.org · Supported
- Kernel module
- ib_uverbs
Check it on the machine
grep -wE 'CONFIG_INFINIBAND|CONFIG_INFINIBAND_USER_ACCESS' /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.
lsmod | grep -w ib_uverbsPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this as a loadable module. Every release with an answer below compiles it as a module on every flavour, so whether the code is in the running kernel depends on whether that module is loaded. The build rule could not be established for 2 releases, so nothing is claimed about those.
- bookworm, trixie?
- forky, sidm
- ?
- not established - no Makefile entry for the affected file
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.
- Build switches
- CONFIG_INFINIBAND, CONFIG_INFINIBAND_USER_ACCESS
- 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
- 2026-06-25 (4 months ago)source
- CVSS
- 7.1 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.12%, higher than 1.9% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- drivers/infiniband
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.17 | 6.18.36 | bd5e818be796 |
| 6.17 | 7.0.13 | 0efbb6b54ff5 |
| 6.17 | 7.1 | 323c98a4ff06 |
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 vulnerable path is reached by a local RDMA uverbs ioctl on /dev/infiniband/uverbsN, specifically RDMA_VERBS_IOCTL selecting UVERBS_METHOD_DMAH_ALLOC. It is not exposed by incoming network packets or remote RDMA traffic.
- AC:LAttack complexity, low
- An attacker can supply an out-of-range UVERBS_ATTR_ALLOC_DMAH_CPU_ID directly in one ioctl, with no race or victim-controlled timing requirement. The only deployment prerequisite is an affected RDMA device exposing the DMAH uverbs method.
- PR:LPrivileges required, low
- The uverbs ioctl path has no CAP_* check for DMAH allocation, and RDMA uverbs devices are designed to be usable by non-root users when the device node is accessible. This requires local low-privileged access rather than real administrator privileges.
- UI:NUser interaction, none
- No victim action is needed after the attacker has local access to the uverbs device. The attacker triggers the bug directly through the ioctl.
- S:UScope, unchanged
- The bug affects kernel RDMA/core processing within the same host kernel security authority. It does not cross a VM, IOMMU, or separate authorization boundary.
- C:HConfidentiality impact, high
- The unchecked cpu_id is passed to cpumask_test_cpu(), which expands to test_bit() on current->cpus_ptr without a bounds check, creating an out-of-bounds kernel memory read. The result influences the returned error/path, making a kernel memory bit oracle defensible.
- I:NIntegrity impact, none
- The identified primitive is an out-of-bounds read of a cpumask bitmap and no kernel out-of-bounds write or control-flow corruption was found on the traced path. Passing the value onward only affects TPH steering-tag allocation if the read happens to pass.
- A:HAvailability impact, high
- Large invalid cpu_id values can trigger CONFIG_DEBUG_PER_CPU_MAPS WARN_ON_ONCE(), and with panic_on_warn this reboots the machine. The same unchecked test_bit() can also fault from an out-of-bounds kernel read, making kernel oops/panic availability impact defensible.