part of the file name in most cases. And even when they do control the
full path, many users would likely find such a path suspicious, which
would likely make it more difficult for an attacker to successfully
trick the user into opening such a path.

Discussion
-----------

Normally, we do not issue Qubes security bulletins for purely "in-VM"
vulnerabilities (like this one) that do not involve crossing the VM
security boundary. However, we have decided to make an exception in this
case, since this is a bug in our code and since qvm-open-in-vm is
specifically intended to operate on untrusted input.

While qvm-open-in-vm is designed to be hardened, keep in mind that
handling less trusted data in a more trusted VM still can be risky for
other reasons, for example:

- Unsafe handling of attacker-controlled paths is an easy mistake to
make in the shell.
- A file explorer could render the thumbnail of an untrusted file with
a buggy parser.
- You might accidentally open the file with an application other than
qvm-open-in-vm, exposing the full attack surface of that application.

Patching
---------

The following package contains the security update that addresses the
vulnerability described in this bulletin:

For Qubes 4.3, in affected templates and standalones:
- qubes-core-agent version 4.3.48

This package will migrate from the security-testing repository to the
current (stable) repository over the next two weeks after being tested
by the community. [2] Once available, the package should be installed
via the Qubes Update tool or its command-line equivalents. [1]

In order for this security update to take effect, all affected templates
must be updated with the package above, then shut down. Afterward, all
qubes based on these templates (including disposables) must be
restarted. All affected standalones must be updated with the package
above.

Credits
--------

This vulnerability was first reported by Giulio Berra. Shortly after, it
was independently reported by Rafal Wojtczuk.

References
-----------

[1] https://doc.qubes-os.org/en/latest/user/how-to-guides/how-to-update.html
[2] https://doc.qubes-os.org/en/latest/user/downloading-installing-upgrading/testing.html

--
The Qubes Security Team
https://www.qubes-os.org/security/



Source: qsb-119-2026.txt (https://github.com/QubesOS/qubes-secpack/blob/2504a9d8fe7979eadaa933359da0981a3c14a7de/QSBs/qsb-119-2026.txt)

Marek Marczykowski-Górecki (https://www.qubes-os.org/team/#marek-marczykowski-g%C3%B3recki)’s PGP signature

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Source: qsb-119-2026.txt.sig.marmarek (https://github.com/QubesOS/qubes-secpack/blob/2504a9d8fe7979eadaa933359da0981a3c14a7de/QSBs/qsb-119-2026.txt.sig.marmarek)

Simon Gaiser (aka HW42) (https://www.qubes-os.org/team/#simon-gaiser-aka-hw42)’s PGP signature

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