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CVE-2026-74397
IB/mlx5: Fix transport-domain rollback and initialize lb mutex earlier
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem drivers/infiniband. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-74397 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 | 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
mlx5_ib_alloc_transport_domain() allocates a transport domain and then may fail in mlx5_ib_enable_lb(). In that case, the allocated TD is leaked. Fix this by deallocating the TD when mlx5_ib_enable_lb() returns an error. Also return 0 explicitly in the no-loopback-capability success branch, and move dev->lb.mutex initialization to mlx5_ib_stage_init_init().
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/hw/mlx5/main.c
- What this is
- MELLANOX MLX5 IB driverMAINTAINERS section matched on drivers/infiniband/hw/mlx5/ · linux-rdma@vger.kernel.org · Supported
- Kernel module
- mlx5_ib
Check it on the machine
grep -wE 'CONFIG_INFINIBAND|CONFIG_MLX5_INFINIBAND' /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 mlx5_ibPrints 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, 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.
- bookwormm
- trixieMnot built on armel/rpi
- forky, sidm
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_INFINIBAND, CONFIG_MLX5_INFINIBAND
- 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
- 0.13%, higher than 2.3% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- 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 |
|---|---|---|
| 4.5 | 6.6.145 | 2c3b2667dad6 |
| 4.5 | 6.12.97 | 37fc3cc0f924 |
| 4.5 | 6.18.40 | 65e344925fa3 |
| 4.5 | 7.1.5 | f88e12c95fc1 |
| 4.5 | 7.2 | e79389115b9d |
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
- Reachable only via local ibverbs syscalls (ioctl/write) on /dev/infiniband/uverbsX through mlx5_ib_alloc_ucontext() and mlx5_ib_create_qp(); not via remote RoCE/IB packet handling.
- AC:LAttack complexity, low
- An attacker can reliably open uverbs and create raw-packet QPs with self-loopback flags to invoke mlx5_ib_enable_lb(); TD leaks are repeatable by looping alloc_ucontext and can force enable_lb failure via memory pressure or firmware errors.
- PR:LPrivileges required, low
- Kernel creates uverbs device nodes as world-accessible (0666); alloc_ucontext and create_qp require no real root/CAP_SYS_ADMIN, only local access to the mlx5 RDMA character device on hosts with the hardware.
- UI:NUser interaction, none
- Exploitation needs only attacker-driven ibverbs calls; no victim interaction such as mounting filesystems, clicking links, or opening files is required.
- S:UScope, unchanged
- Impact stays within the host kernel mlx5 RDMA driver scope; this is not a VM escape, IOMMU/DMA boundary bypass, or other cross-security-authority compromise per kernel CVSS guidance.
- C:HConfidentiality impact, high
- Locking an uninitialized dev->lb.mutex in mlx5_ib_enable_lb()/disable_lb is undefined behavior that can corrupt kernel memory and be leveraged for arbitrary kernel memory disclosure.
- I:HIntegrity impact, high
- Uninitialized mutex use during ucontext transport-domain setup or raw-packet QP creation can corrupt adjacent kernel structures and enable arbitrary write or control-flow hijack primitives.
- A:HAvailability impact, high
- Invalid mutex operations can kernel panic/oops; repeated alloc_ucontext without TD rollback on mlx5_ib_enable_lb() failure exhausts transport domains and denies further RDMA context/QP creation (DoS).