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CVE-2026-64033
RDMA/rtrs: Fix use-after-free in path file creation cleanup
Published 2026-07-19 (3 months ago) by the Linux kernel CNA. Subsystem drivers/infiniband. Debian urgency: not yet assigned.
Debian does not build this code. The per-release build detail is under "Where it lives" below.
What to do, per Debian release
Debian's own status for CVE-2026-64033 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 | fixed | 6.1.176-1 | Update the kernel and reboot. Fixed in 6.1.176-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.94-1 | Update the kernel and reboot. Fixed in 6.12.94-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
In the error path of rtrs_srv_create_path_files(), the sysfs root folders may already have been created and srv_path->kobj may already have been initialized. If a later step fails, the cleanup currently calls kobject_put(&srv_path->kobj) before rtrs_srv_destroy_once_sysfs_root_folders(srv_path). kobject_put() may drop the last reference to srv_path->kobj and invoke the release callback, rtrs_srv_release(), which frees srv_path. The following call to rtrs_srv_destroy_once_sysfs_root_folders(srv_path) then dereferences srv_path internally to access srv_path->srv, resulting in a use-after-free. This failure path is reached before rtrs_srv_create_path_files() returns success, so the successful-path lifetime handling is not involved. Fix this by destroying the sysfs root folders before calling kobject_put(&srv_path->kobj), so srv_path is still valid while the helper accesses it. This issue was found by a static analysis tool I am developing.
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/ulp/rtrs/rtrs-srv-sysfs.c
- What this is
- RTRS TRANSPORT DRIVERSMAINTAINERS section matched on drivers/infiniband/ulp/rtrs/ · linux-rdma@vger.kernel.org · Maintained
- Kernel module
- none to look for. The file would have gone into rtrs_server, and Debian does not compile it into that module, so finding rtrs_server in lsmod would say nothing about this CVE.
Check it on the machine
grep -wE 'CONFIG_INFINIBAND|CONFIG_INFINIBAND_RTRS|CONFIG_INFINIBAND_RTRS_SERVER' /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 does not build this code. In 4 releases below, every kernel flavour Debian publishes has the switch off, so the vulnerable file is compiled into no kernel binary Debian ships.
- bookworm, trixie, forky, sidn
- n
- not enabled on any flavour - this release does not build the code
- Build switches
- CONFIG_INFINIBAND, CONFIG_INFINIBAND_RTRS, CONFIG_INFINIBAND_RTRS_SERVER
- 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
- 2026-07-19 (3 months ago)source
- CVSS
- 9.8 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.49%, higher than 40.7% 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 |
|---|---|---|
| 5.15.61 | 5.15.209 | 01e42aabaf76 |
| 5.17 | 6.1.175 | 548f3956e53a |
| 5.17 | 6.6.142 | 00904a73272b |
| 5.17 | 6.12.92 | 92060ab1c511 |
| 5.17 | 6.18.34 | eae62c5451e6 |
| 5.17 | 7.0.11 | b0e9706fb285 |
| 5.17 | 7.1 | 5b7437339011 |
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:NAttack vector, network
- The vulnerable code runs in the RTRS server RDMA CM handler when a remote peer completes connection setup and sends RTRS_MSG_INFO_REQ; the server listens on network addresses via rdma_listen() on IPv6 and IB port spaces (default port 1234, used by rnbd-server).
- AC:LAttack complexity, low
- This is a deterministic cleanup-order UAF, not a race; once the attacker drives sysfs creation into an error path (e.g., via parallel connection attempts causing allocation failures), the bug triggers reliably on every failed setup.
- PR:NPrivileges required, none
- No Linux credentials are required; any remote RTRS/RNBD client that can reach the server's RDMA listener can complete the pre-authentication connection and info-request handshake that calls rtrs_srv_create_path_files().
- UI:NUser interaction, none
- Exploitation is fully automated through the RTRS wire protocol and requires no action from a local user or administrator on the target host.
- S:UScope, unchanged
- Impact is confined to kernel memory corruption and privilege escalation on the RTRS server host; it does not cross a VM, container, or IOMMU security boundary by itself.
- C:HConfidentiality impact, high
- The use-after-free dereferences freed srv_path memory (including srv_path->srv) during cleanup, which can leak kernel heap contents or be turned into an arbitrary read primitive through heap grooming.
- I:HIntegrity impact, high
- UAF on a kernel heap object enables control of freed memory contents and can be leveraged for arbitrary kernel writes or code execution via heap spraying and structure reuse.
- A:HAvailability impact, high
- The UAF dereference during error cleanup can cause kernel oops/panic on the RTRS server, and successful exploitation can crash or fully compromise the host.