Artifex MuJS 1.0.2 Integer Overflow

2018.01.29
Risk: Medium
Local: No
Remote: Yes
CWE: CWE-189


CVSS Base Score: 4.3/10
Impact Subscore: 2.9/10
Exploitability Subscore: 8.6/10
Exploit range: Remote
Attack complexity: Medium
Authentication: No required
Confidentiality impact: None
Integrity impact: None
Availability impact: Partial

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 (https://www.artifex.com/) # Software Link: https://github.com/ccxvii/mujs # 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 https://github.com/ccxvii/ mujs/blob/81388eb40d29f10599ac30dde90e683a3c254375/jsdtoa.c#L714 exp = -exp; the value of "exp" is still negative (cause integer declaration). Fixed in commit 25821e6d74fab5fcc200fe5e818362e03e114428 ( http://git.ghostscript.com/?p=mujs.git;a=commit;h= 25821e6d74fab5fcc200fe5e818362e03e114428) Please let me know if you need more info. Andrea Sindoni


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