A vulnerability has been found and corrected in pango:

It was discovered that pango did not check for memory reallocation
failures in hb_buffer_ensure() function. This could trigger a NULL
pointer dereference in hb_buffer_add_glyph(), where possibly untrusted
input is used as an index used for accessing members of the incorrectly
reallocated array, resulting in the use of NULL address as the base
array address. This can result in application crash or, possibly,
code execution (CVE-2011-1002).

The updated packages have been patched to correct this issue.