bsdiff and bspatch are tools for building and applying patches to binary files.
It was discovered that the implementation of bspatch did not check for a negative value on numbers of bytes read from the diff and extra streams.
A remote attacker could entice a user to apply a specially crafted patch using bspatch, possibly resulting in execution of arbitrary code with the privileges of the process or a Denial of Service condition.
There is no known workaround at this time.
All Binary diff users should upgrade to the latest version:
# emerge --sync # emerge --ask --oneshot --verbose ">=dev-util/bsdiff-4.3-r4"