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CVE-2026-63860
RDMA/core: Prefer NLA_NUL_STRING
Published 2026-07-19 (3 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-2026-63860 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 | 7.0.10-1 | Update the kernel and reboot. Fixed in 7.0.10-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.10-1 | Update the kernel and reboot. Fixed in 7.0.10-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
These attributes are evaluated as c-string (passed to strcmp), but NLA_STRING doesn't check for the presence of a \0 terminator. Either this needs to switch to nla_strcmp() and needs to adjust printf fmt specifier to not use plain %s, or this needs to use NLA_NUL_STRING. As the code has been this way for long time, it seems to me that userspace does include the terminating nul, even tough its not enforced so far, and thus NLA_NUL_STRING use is the simpler solution.
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/iwpm_msg.c
- What this is
- INFINIBAND SUBSYSTEMMAINTAINERS section matched on drivers/infiniband/ · linux-rdma@vger.kernel.org · Supported
- Kernel module
- iw_cm
Check it on the machine
grep -w CONFIG_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 iw_cmPrints 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 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.
- bookworm, trixie, forky, sidm
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
- Build switch
- CONFIG_INFINIBAND
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
- 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
- 0.14%, higher than 3.0% 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 |
|---|---|---|
| 3.16 | 5.10.258 | fcd07d3b8ee7 |
| 3.16 | 5.15.209 | 87111356d58d |
| 3.16 | 6.1.175 | abda65bdd130 |
| 3.16 | 6.6.141 | 137b5918931d |
| 3.16 | 6.12.91 | 5877c043398d |
| 3.16 | 6.18.33 | f2c7b39dde2e |
| 3.16 | 7.0.10 | c26a0052ccee |
| 3.16 | 7.1 | 6ed3d14fc45d |
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 bug is reached when userspace sends crafted NETLINK_RDMA (protocol 20) messages to the iWARP Port Mapper netlink handlers in `iwpm_register_pid_cb()` and `iwpm_mapping_info_cb()`, not from remote network packets.
- AC:LAttack complexity, low
- An attacker fully controls the netlink attribute payload and can send a maximal-length string without a NUL terminator to reliably trigger unbounded `strcmp()` reads; no race or victim-dependent state is required beyond reaching the handler.
- PR:NPrivileges required, none
- IWPM netlink ops lack `RDMA_NL_ADMIN_PERM`, and `netlink_sendmsg()` only enforces `CAP_NET_ADMIN` when `dst_pid` or `dst_group` is non-zero, so an unprivileged local process can send messages to the kernel RDMA netlink socket without capabilities or user-namespace tricks.
- UI:NUser interaction, none
- Exploitation requires only a local process sending a crafted netlink message; no victim interaction such as mounting a filesystem or opening a device is needed.
- S:UScope, unchanged
- Impact is confined to kernel RDMA/iWARP port-mapper state (e.g., `iwpm_user_pid`, mapping tables) within the same kernel security authority and does not cross VM, container, or IOMMU boundaries.
- C:HConfidentiality impact, high
- `NLA_STRING` does not enforce a NUL terminator, yet `strcmp()` reads until `\0`, causing an out-of-bounds kernel read past the attribute boundary; error paths also pass the pointer to `%s` in `pr_info()`, enabling further kernel memory disclosure.
- I:HIntegrity impact, high
- By sending exactly 19 bytes of `iWarpPortMapperUser` without a terminator, an attacker can make `strcmp()` read a NUL from NLA padding and pass validation, hijacking `iwpm_user_pid` and redirecting subsequent iWARP port-mapping operations to attacker-controlled userspace.
- A:HAvailability impact, high
- Unbounded `strcmp()` on a non-NUL-terminated netlink attribute can read beyond the skb buffer and trigger a kernel page fault/oops, and successful port-mapper impersonation can disrupt iWARP connectivity on affected systems.