I'm pleased to announce the release of nbdkit 1.48. nbdkit is an NBD server, for Network Block Devices, with a flexible plugin-based architecture and permissive license. Note there are some minor security issues that are fixed in this release. If you're using one of the affected plugins or filters then upgrading is recommended. Thanks Vladimir Vasilev for coordinating these. The release notes are attached below or you can see them online here: https://libguestfs.org/nbdkit-release-notes-1.48.1.html Tarballs are available here: https://download.libguestfs.org/nbdkit/1.48-stable/ Distro updates coming soon. Rich. These are the release notes for nbdkit stable release 1.48. This de‐ scribes the major changes since 1.46. nbdkit 1.48.0 was released on 14 July 2026. Security Fix minor denial of service vulnerability in nbdkit-blocksize-policy-fil‐ ter(1) (Eric Blake). Fix a minor issue with concurrent connections in nbdkit-golang-plugin(3) (AISLE AI security scanner). Fix two minor denial of service vulnerabilities in nbdkit-split-plugin(1) (AISLE AI security scanner). Fix a memory leak and document a potential denial of service vulnerability (although working by design) in nbdkit-cow-filter(1) (AISLE AI security scanner). Fix a memory leak in server option parsing (AISLE AI security scanner). Plugins In nbdkit-file-plugin(1) we no longer advertize minimum_io_size larger than 64K even for backing storage like LVM that could support it. This is because the NBD protocol itself does not support larger sizes (thanks Ni‐ jin Ashok, Eric Blake, Mikulas Patocka). In nbdkit-sparse-random-plugin(1) the block size is now configurable at run time. In nbdkit-vddk-plugin(1) test against VDDK 9.0.1.0. Filters New nbdkit-xor-filter(1) simply XORs a pattern or PRNG with the underlying data, providing simple obfuscation. nbdkit-cow-filter(1) now supports arbitrarily large overlays, even when the filesystem used to store the overlay has file size limitations (eg. 16T on ext4) nbdkit-ip-filter(1) now allows you to filter on loopback addresses. Language bindings In nbdkit-ocaml-plugin(3) a new "NBDKit.Error" exception can be used to throw a precise errno with error message. Also "Unix_error" exception is now translated to errno and error, and there are other improvements to "Failure" and "Invalid_argument" exceptions. In nbdkit-ocaml-plugin provide convenience functions for converting bytes and string types into "NBDKit.buf" Server nbdkit --port=0 can be used to let the kernel pick a free listening port. "LISTEN_FDNAMES" is now parsed for socket activation, although we do noth‐ ing aside from printing socket names. API New nbdkit_debug_hexdiff(3) function which shows the differences between two binary buffers. New nbdkit_name(3) function which returns the nbdkit --name parameter to plugins and filters. New nbdkit_timestamp(3) function which returns a timestamp suitable for log messages. When parsing human sizes (eg. in nbdkit_parse_size(3)), allow hex and oc‐ tal sizes, and allow "_" before the scaling factor. For example "0x1_E" is parsed as 1 exabyte. nbdkit_read_password(3) "password=-" now reads the password from /dev/tty on operating systems that support this. Documentation Document how to disable shadow stack support for loading plugins that were not compiled with this feature. Tests A new interoperability test with Digital Ocean's Go-NBD client library was added. Fix CI (Daniel Berrangé). Build Setting "NBDKIT_VALGRIND_MASSIF=1" will run nbdkit under valgrind massif (for memory profiling). SEE ALSO nbdkit(1). AUTHORS Authors of nbdkit 1.48: Daniel P. Berrangé Eric Blake Christopher Byrne Richard W.M. Jones Alan Somers COPYRIGHT Copyright Red Hat LICENSE Redistribution and use in source and binary forms, with or without modifi‐ cation, are permitted provided that the following conditions are met: • Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. • Redistributions in binary form must reproduce the above copyright no‐ tice, this list of conditions and the following disclaimer in the doc‐ umentation and/or other materials provided with the distribution. • Neither the name of Red Hat nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SER‐ VICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABIL‐ ITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAM‐ AGE. nbdkit-1.48.0 2026-07-14 nbdkit-release-notes-1.48(1) -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-builder quickly builds VMs from scratch http://libguestfs.org/virt-builder.1.html