I believe I'm experiencing the same bug. On a fresh install of Ubuntu 11.10 on a Dell Dimension 2400, using xvnc4viewer (in listen mode) I got the following output when accepting a reverse connection from another PC: vncviewer -listen VNC Viewer Free Edition 4.1.1 for X - built Sep 7 2011 11:20:11 Copyright (C) 2002-2005 RealVNC Ltd. See http://www.realvnc.com for information on VNC. Fri Nov 18 04:09:13 2011 main: Listening on port 5500 Fri Nov 18 04:09:17 2011 CConn: Accepted connection from 0.0.0.0::55083 *** stack smashing detected ***: vncviewer terminated ======= Backtrace: ========= /lib/i386-linux-gnu/libc.so.6(__fortify_fail+0x45)[0x32b8d5] /lib/i386-linux-gnu/libc.so.6(+0xe7887)[0x32b887] vncviewer[0x8082f91] vncviewer[0x807e534] vncviewer[0x805064b] vncviewer[0x805a056] /lib/i386-linux-gnu/libc.so.6(__libc_start_main+0xf3)[0x25d113] vncviewer[0x804c6b1] ======= Memory map: ======== 00110000-00121000 r-xp 00000000 08:01 1444223 /usr/lib/i386-linux-gnu/libXext.so.6.4.0 00121000-00122000 r--p 00010000 08:01 1444223 /usr/lib/i386-linux-gnu/libXext.so.6.4.0 00122000-00123000 rw-p 00011000 08:01 1444223 /usr/lib/i386-linux-gnu/libXext.so.6.4.0 00123000-00126000 r-xp 00000000 08:01 655025 /lib/i386-linux-gnu/libdl-2.13.so 00126000-00127000 r--p 00002000 08:01 655025 /lib/i386-linux-gnu/libdl-2.13.so 00127000-00128000 rw-p 00003000 08:01 655025 /lib/i386-linux-gnu/libdl-2.13.so 00128000-0012a000 r-xp 00000000 08:01 1444213 /usr/lib/i386-linux-gnu/libXau.so.6.0.0 0012a000-0012b000 r--p 00001000 08:01 1444213 /usr/lib/i386-linux-gnu/libXau.so.6.0.0 0012b000-0012c000 rw-p 00002000 08:01 1444213 /usr/lib/i386-linux-gnu/libXau.so.6.0.0 0012c000-00135000 r-xp 00000000 08:01 1444235 /usr/lib/i386-linux-gnu/libXrender.so.1.3.0 00135000-00136000 r--p 00008000 08:01 1444235 /usr/lib/i386-linux-gnu/libXrender.so.1.3.0 00136000-00137000 rw-p 00009000 08:01 1444235 /usr/lib/i386-linux-gnu/libXrender.so.1.3.0 00226000-00242000 r-xp 00000000 08:01 655035 /lib/i386-linux-gnu/libgcc_s.so.1 00242000-00243000 r--p 0001b000 08:01 655035 /lib/i386-linux-gnu/libgcc_s.so.1 00243000-00244000 rw-p 0001c000 08:01 655035 /lib/i386-linux-gnu/libgcc_s.so.1 00244000-003ba000 r-xp 00000000 08:01 655014 /lib/i386-linux-gnu/libc-2.13.so 003ba000-003bc000 r--p 00176000 08:01 655014 /lib/i386-linux-gnu/libc-2.13.so 003bc000-003bd000 rw-p 00178000 08:01 655014 /lib/i386-linux-gnu/libc-2.13.so 003bd000-003c0000 rw-p 00000000 00:00 0 00421000-0043f000 r-xp 00000000 08:01 655001 /lib/i386-linux-gnu/ld-2.13.so 0043f000-00440000 r--p 0001d000 08:01 655001 /lib/i386-linux-gnu/ld-2.13.so 00440000-00441000 rw-p 0001e000 08:01 655001 /lib/i386-linux-gnu/ld-2.13.so 004b0000-004b4000 r-xp 00000000 08:01 1444225 /usr/lib/i386-linux-gnu/libXfixes.so.3.1.0 004b4000-004b5000 r--p 00003000 08:01 1444225 /usr/lib/i386-linux-gnu/libXfixes.so.3.1.0 004b5000-004b6000 rw-p 00004000 08:01 1444225 /usr/lib/i386-linux-gnu/libXfixes.so.3.1.0 004e4000-0050c000 r-xp 00000000 08:01 655044 /lib/i386-linux-gnu/libm-2.13.so 0050c000-0050d000 r--p 00028000 08:01 655044 /lib/i386-linux-gnu/libm-2.13.so 0050d000-0050e000 rw-p 00029000 08:01 655044 /lib/i386-linux-gnu/libm-2.13.so 00598000-005a1000 r-xp 00000000 08:01 1444217 /usr/lib/i386-linux-gnu/libXcursor.so.1.0.2 005a1000-005a2000 r--p 00008000 08:01 1444217 /usr/lib/i386-linux-gnu/libXcursor.so.1.0.2 005a2000-005a3000 rw-p 00009000 08:01 1444217 /usr/lib/i386-linux-gnu/libXcursor.so.1.0.2 005f0000-005f5000 r-xp 00000000 08:01 1444221 /usr/lib/i386-linux-gnu/libXdmcp.so.6.0.0 005f5000-005f6000 r--p 00004000 08:01 1444221 /usr/lib/i386-linux-gnu/libXdmcp.so.6.0.0 005f6000-005f7000 rw-p 00005000 08:01 1444221 /usr/lib/i386-linux-gnu/libXdmcp.so.6.0.0 0074c000-0075f000 r-xp 00000000 08:01 655097 /lib/i386-linux-gnu/libz.so.1.2.3.4 0075f000-00760000 r--p 00012000 08:01 655097 /lib/i386-linux-gnu/libz.so.1.2.3.4 00760000-00761000 rw-p 00013000 08:01 655097 /lib/i386-linux-gnu/libz.so.1.2.3.4 0078b000-00869000 r-xp 00000000 08:01 1444476 /usr/lib/i386-linux-gnu/libstdc++.so.6.0.16 00869000-0086a000 ---p 000de000 08:01 1444476 /usr/lib/i386-linux-gnu/libstdc++.so.6.0.16 0086a000-0086e000 r--p 000de000 08:01 1444476 /usr/lib/i386-linux-gnu/libstdc++.so.6.0.16 0086e000-0086f000 rw-p 000e2000 08:01 1444476 /usr/lib/i386-linux-gnu/libstdc++.so.6.0.16 0086f000-00876000 rw-p 00000000 00:00 0 00b34000-00c65000 r-xp 00000000 08:01 1444211 /usr/lib/i386-linux-gnu/libX11.so.6.3.0 00c65000-00c66000 ---p 00131000 08:01 1444211 /usr/lib/i386-linux-gnu/libX11.so.6.3.0 00c66000-00c67000 r--p 00131000 08:01 1444211 /usr/lib/i386-linux-gnu/libX11.so.6.3.0 00c67000-00c69000 rw-p 00132000 08:01 1444211 /usr/lib/i386-linux-gnu/libX11.so.6.3.0 00c69000-00c6a000 rw-p 00000000 00:00 0 00f4e000-00f6b000 r-xp 00000000 08:01 1444509 /usr/lib/i386-linux-gnu/libxcb.so.1.1.0 00f6b000-00f6c000 r--p 0001c000 08:01 1444509 /usr/lib/i386-linux-gnu/libxcb.so.1.1.0 00f6c000-00f6d000 rw-p 0001d000 08:01 1444509 /usr/lib/i386-linux-gnu/libxcb.so.1.1.0 00fab000-00fac000 r-xp 00000000 00:00 0 [vdso] 08048000-08099000 r-xp 00000000 08:01 1439882 /usr/bin/xvnc4viewer 0809a000-0809b000 r--p 00051000 08:01 1439882 /usr/bin/xvnc4viewer 0809b000-0809c000 rw-p 00052000 08:01 1439882 /usr/bin/xvnc4viewer 0809c000-0809d000 rw-p 00000000 00:00 0 08daa000-08dcb000 rw-p 00000000 00:00 0 [heap] b7736000-b773b000 rw-p 00000000 00:00 0 b774c000-b774e000 rw-p 00000000 00:00 0 bfaf3000-bfb14000 rw-p 00000000 00:00 0 [stack]