CHMlib: User-assisted remote execution of arbitrary code

Background

CHMlib is a library for the MS CHM (Compressed HTML) file format plus extracting and HTTP server utils.

Description

When certain CHM files that contain tables and objects stored in pages are parsed by CHMlib, an unsanitized value is passed to the alloca() function resulting in a shift of the stack pointer to arbitrary memory locations.

Impact

An attacker could entice a user to open a specially crafted CHM file, resulting in the execution of arbitrary code with the permissions of the user viewing the file.

Workaround

There is no known workaround at this time.

Resolution

All CHMlib users should upgrade to the latest version:

 # emerge --sync
 # emerge --ask --oneshot --verbose ">=dev-libs/chmlib-0.39"