Public Vulnerability Reports

QNX Neutrino RTOS passwd Command Buffer Overflow



QNX Neutrino RTOS is a real-time operating system designed for use in
embedded systems. More information about is available at


Local exploitation of a buffer overflow in QNX Neutrino RTOS's (QNX)
'passwd' command allows attackers to gain root privileges. The problem
specifically exists in the parsing of a long string passed as the first
argument to the set user id (setuid) binary 'passwd'. The 'passwd'
command is intended for changing a users password. A string larger then
approximately 4000 bytes causes a stack overflow directly overwriting
the stored return address and allowing an attacker to seize CPU control
and eventually execute arbitrary code under root privileges.


Any authenticated local attacker can exploit this vulnerability to gain
super-user (root) privileges on the affected system.


iDefense has confirmed the existence of these vulnerabilities in QNX
Neutrino RTOS version 6.2.0. Earlier versions are suspected to be
susceptible to exploitation as well.


Clear the set user id or execute bits from the affected binary or remove
it entirely.


This issue has been corrected in QNX Momentics 6.3.0 SP3 and later versions. A patch is also available for 6.3.0, 6.3.0 SP1, and 6.3.0 SP2 (Patch ID:270). Please contact your QNX representative, or visit to obtain these patches.


A Mitre Corp. Common Vulnerabilities and Exposures (CVE) number has not
been assigned yet.


06/04/2004 Initial vendor notification
02/07/2006 Public disclosure


Texonet ( is credited with this discovery.

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