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CVE-2026-53188
RDMA/core: Validate the passed in fops for ib_get_ucaps()
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-2026-53188 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
Sashiko pointed out it is not safe to rely only on the devt because char/block alias so if the user finds a block device with the same dev_t it can masquerade as a ucap cdev fd. Test the f_ops to only accept authentic cdevs.
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/ucaps.c
- What this is
- INFINIBAND SUBSYSTEMMAINTAINERS section matched on drivers/infiniband/ · linux-rdma@vger.kernel.org · Supported
- Kernel module
- ib_uverbs_support
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_uverbs_supportPrints 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
- 8.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.13%, higher than 2.1% 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 |
|---|---|---|
| 6.15 | 6.18.36 | 96b6e98ff12d |
| 6.15 | 7.0.13 | aa181287ebdc |
| 6.15 | 7.1 | 4a1b1ac27446 |
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 locally through the RDMA uverbs character device by submitting GET_CONTEXT with a user-controlled fd array.
- AC:LAttack complexity, low
- There is no race or fragile memory condition; on a system with a matching accessible block-device dev_t, exploitation is a straightforward fd substitution.
- PR:LPrivileges required, low
- An unprivileged local user can open the world-accessible uverbs device, and the bypass avoids the intended root-only UCAP character device permission check.
- UI:NUser interaction, none
- No victim action is required once the attacker can run local code and open the relevant device files.
- S:CScope, changed
- The bypass can grant mlx5 RDMA control capabilities including other-VHCA control, plausibly affecting HCA/vport resources outside the attacker's normal RDMA security context.
- C:HConfidentiality impact, high
- Unauthorized RDMA control and flow steering can expose or redirect RDMA traffic and resources that should require an explicitly granted UCAP.
- I:HIntegrity impact, high
- The attacker can obtain privileged RDMA/HCA control capabilities that may allow modification or redirection of RDMA flow state and other protected device behavior.
- A:HAvailability impact, high
- The same unauthorized control can be used to drop, disrupt, or exhaust RDMA/HCA resources, causing loss of availability for affected RDMA workloads.