A critical stack overflow vulnerability was discovered in the libxslt library when handling the dyn:map() function from the EXSLT extension. The vulnerability allows an attacker to cause a denial of service (DoS) via a specially crafted XSLT document containing the recursive dyn:map(., .) call.

The main reason of the vulnerability is that the exsltDynMapFunction function in libexslt/dynamic.c doesn’t contain a recursion depth check. When handling dyn:map(., .) where the second parameter contains a recursive call to the same function, infinite recursion occurs until the program stack is exhausted.