CVE-2026-97993

What the bug is

vhost_vdpa_set_config_call() swaps the eventfd_ctx_fdget() return value into v->config_ctx before checking it, so on failure the field briefly holds an ERR_PTR: ctx = fd == VHOST_FILE_UNBIND ? NULL : eventfd_ctx_fdget(fd); swap(ctx, v->config_ctx); if (!IS_ERR_OR_NULL(ctx)) eventfd_ctx_put(ctx); if (IS_ERR(v->config_ctx)) { long ret = PTR_ERR(v->config_ctx); v->config_ctx = NULL; return ret; } Commit 0bde59c1723a ("vhost-vdpa: set v->config_ctx to NULL if eventfd_ctx_fdget() fails") added that clearing, and spelled out the invariant the rest of the file relies on: "we consider 'v->config_ctx' valid if it is not NULL". The window between the swap and the clearing still breaks it. vhost_vdpa_config_cb() only tests for NULL, so a config interrupt delivered inside the window hands the ERR_PTR to eventfd_signal(). Check the fd before installing it instead. That closes the window and matches how vhost_vring_ioctl() handles the same failure for the vq call fd. It also stops a rejected fd from tearing down a config interrupt that was working: until now the swap replaced the live context and put it, so after an EBADF the device silently stopped delivering config interrupts until userspace installed a new fd.

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/vhost/vdpa.c

What this is

VIRTIO HOST (VHOST)MAINTAINERS section matched on drivers/vhost/ · kvm@vger.kernel.org · Maintained

Kernel module

none to look for. The file would have gone into vhost_vdpa, and Debian does not compile it into that module, so finding vhost_vdpa in lsmod would say nothing about this CVE.

Check it on the machine

grep -wE 'CONFIG_VHOST|CONFIG_VHOST_IOTLB|CONFIG_VHOST_RING|CONFIG_VHOST_VDPA' /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 5 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, sid, bookworm · linux-6.12n

n

not enabled on any flavour - this release does not build the code

Build switches

CONFIG_VHOST, CONFIG_VHOST_IOTLB, CONFIG_VHOST_RING, CONFIG_VHOST_VDPA

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

2026-09-25 (24 days ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.21%, higher than 10.5% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

not yet assignedsource

Subsystem

drivers/vhost

Upstream fixes

The versions the CNA records as introducing and fixing this, and the commit for each. source

Introduced	Fixed in	Commit
5.8	5.10.271	e260dc9fbfda
5.8	5.15.222	66e73fa18910
5.8	6.1.189	4fde085eb839
5.8	6.6.158	59fc7c1c6b4d
5.8	6.12.111	388c678639a0
5.8	6.18.53	65faf9eaa00e
5.8	7.2.7	6b20b40f020b
5.8	7.3	e74a9fa50749

Debian advisories