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============================================================================= FreeBSD-SA-26:07.nvmf Security Advisory
The FreeBSD Project

Topic: Remote denial of service via null pointer dereference

Category: core
Module: nvmf
Announced: 2026-03-26
Credits: Nikolay Denev <ndenev@gmail.com>
Affects: FreeBSD 15.0
Corrected: 2026-03-25 01:29:47 UTC (stable/15, 15.0-STABLE)
2026-03-26 01:11:19 UTC (releng/15.0, 15.0-RELEASE-p5)
CVE Name: CVE-2026-4652

For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the following sections, please visit <URL:https://security.FreeBSD.org/>.

I. Background

The nvmf driver implements the kernel component of an NVMe over Fabrics
host.

The CONNECT command is used to create connections (queue pairs) that
carry NVMe read/write commands over the network. For I/O queues, this
is commonly referred to as an I/O CONNECT.

II. Problem Description

On a system exposing an NVMe/TCP target, a remote client can trigger
a kernel panic by sending a CONNECT command for an I/O queue with a
bogus or stale CNTLID.

III. Impact

An attacker with network access to the NVMe/TCP target can trigger
an unauthenticated Denial of Service condition on the affected machine.

IV. Workaround

No workaround is available.

V. Solution

Upgrade your vulnerable system to a supported FreeBSD stable or release / security branch (releng) dated after the correction date and reboot.

Perform one of the following:

1) To update your vulnerable system installed from base system packages:

Systems running a 15.0-RELEASE version of FreeBSD on the amd64 or arm64 platforms, which were installed using base system packages, can be updated
via the pkg(8) utility:

# pkg upgrade -r FreeBSD-base
# shutdown -r +10min "Rebooting for a security update"

2) To update your vulnerable system installed from binary distribution sets:

Systems running a RELEASE version of FreeBSD on the amd64 or arm64 platforms, which were not installed using base system packages, can be updated via the freebsd-update(8) utility:

# freebsd-update fetch
# freebsd-update install
# shutdown -r +10min "Rebooting for a security update"

3) To update your vulnerable system via a source code patch:

The following patches have been verified to apply to the applicable
FreeBSD release branches.

a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.

# fetch https://security.FreeBSD.org/patches/SA-26:07/nvmf.patch
# fetch https://security.FreeBSD.org/patches/SA-26:07/nvmf.patch.asc
# gpg --verify nvmf.patch.asc

b) Apply the patch. Execute the following commands as root:

# cd /usr/src
# patch < /path/to/patch

c) Recompile your kernel as described in <URL:https://www.FreeBSD.org/handbook/kernelconfig.html> and reboot the
system.

VI. Correction details

This issue is corrected as of the corresponding Git commit hash in the following stable and release branches:

Branch/path Hash Revision
- ------------------------------------------------------------------------- stable/15/ b1d32521747f stable/15-n282694 releng/15.0/ 48766013063a releng/15.0-n281012
- -------------------------------------------------------------------------

Run the following command to see which files were modified by a
particular commit:

# git show --stat <commit hash>

Or visit the following URL, replacing NNNNNN with the hash:

<URL:https://cgit.freebsd.org/src/commit/?id=NNNNNN>

To determine the commit count in a working tree (for comparison against
nNNNNNN in the table above), run:

# git rev-list --count --first-parent HEAD

VII. References

<URL:https://www.cve.org/CVERecord?id=CVE-2026-4652>

The latest revision of this advisory is available at <URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-26:07.nvmf.asc> -----BEGIN PGP SIGNATURE-----

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