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Daniel P. Berrangé
68da70aae7
When we have an XML parse error, libxml2 invokes a callback that receives pointers to the start of the document being parsed and the location where the error was triggered. In the case of a document that contains 100's of empty lines (ie a sequence of newlines), at some point libxml2 will advance the base pointer discarding the useful context. Thus when catchXMLError then searches backwards to discard empty lines and look for the context element, it will eventually get to the start of the string. When this happens the virBuffer that holds the context string ends up empty and then catchXMLError will dereference a NULL pointer. In almost all cases, the APIs which accept XML documents from the user are behind the primary read-write socket, however, the CPU baseline API is exposed to the read-only socket. Thus an unprivileged user can trigger a denial of service by crashing the libvirt daemons with a malicious XML document. Check for this empty string condition and skip inclusion of the XML document context in the error message. Fixes: CVE-2026-61478 Reported-by: Rx <rx1513@altlinux.org> Reviewed-by: Peter Krempa <pkrempa@redhat.com> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
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==============================
Libvirt API for virtualization
==============================
Libvirt provides a portable, long term stable C API for managing the
virtualization technologies provided by many operating systems. It
includes support for QEMU, KVM, Xen, LXC, bhyve, Virtuozzo, VMware
vCenter and ESX, VMware Desktop, Hyper-V, VirtualBox and the POWER
Hypervisor.
For some of these hypervisors, it provides a stateful management
daemon which runs on the virtualization host allowing access to the
API both by non-privileged local users and remote users.
Layered packages provide bindings of the libvirt C API into other
languages including Python, Perl, PHP, Go, Java, OCaml, as well as
mappings into object systems such as GObject, CIM and SNMP.
Further information about the libvirt project can be found on the
website:
https://libvirt.org
License
=======
The libvirt C API is distributed under the terms of GNU Lesser General
Public License, version 2.1 (or later). Some parts of the code that are
not part of the C library may have the more restrictive GNU General
Public License, version 2.0 (or later). See the files ``COPYING.LESSER``
and ``COPYING`` for full license terms & conditions.
Installation
============
Instructions on building and installing libvirt can be found on the website:
https://libvirt.org/compiling.html
Contributing
============
The libvirt project welcomes contributions in many ways. For most components
the best way to contribute is to send patches to the primary development
mailing list. Further guidance on this can be found on the website:
https://libvirt.org/contribute.html
Contact
=======
The libvirt project has two primary mailing lists:
* users@lists.libvirt.org (**for user discussions**)
* devel@lists.libvirt.org (**for development only**)
Further details on contacting the project are available on the website:
https://libvirt.org/contact.html