libguestfs is a library for accessing and modifying guest disk images. It was found that guestfish, which enables shell scripting and command line access to libguestfs, insecurely created the temporary directory used to store the network socket when started in server mode (using the "--listen" option). If guestfish were run with the "--listen" option, a local attacker could use this flaw to intercept and modify other users' guestfish commands, allowing them to perform arbitrary guestfish actions (such as modifying virtual machines) with the privileges of a different user, or use this flaw to obtain authentication credentials.

Acknowledgements:

This issue was discovered by Michael Scherer of the Red Hat Regional IT team.

A buffer overflow was found in getkeys getkeys()

When calculating the greatest possible number of matching keys in getkeys(), the current expression

MIN (1, ks->nrkeys)

is wrong -- it will return at most 1.

If all "nrkeys" keys match however, then we require "nrkeys" non-NULL entries in the result array; in other words, we need

MAX (1, ks->nrkeys)

(The comment just above the expression is correct; the code is wrong.)

This buffer overflow is easiest to trigger in those guestfs tools that parse the "--key" option in C; that is, with "OPTIONkey". For example, the command

$ virt-cat $(seq -f '--key /dev/sda2:key:%g' 200) -d DOMAIN /no-such-file

which passes 200 (different) passphrases for the LUKS-encrypted block device "/dev/sda2", crashes with a SIGSEGV.

libguestfs before 1.5.23, as used in virt-v2v, virt-inspector 1.5.3 and earlier, and possibly other products, when a raw-format disk image is used, allows local guest OS administrators to read files from the host via a crafted (1) qcow2, (2) VMDK, or (3) VDI header, related to lack of support for a disk format specifier.