Buffer Overflow Detected (and reported.)

*** buffer overflow detected ***: /usr/local/bin/tclsh8.6 terminated
======= Backtrace: =========
/lib/x86_64-linux-gnu/libc.so.6(+0x777e5)[0x7f6a768c97e5]
/lib/x86_64-linux-gnu/libc.so.6(__fortify_fail+0x5c)[0x7f6a7696b15c]
/lib/x86_64-linux-gnu/libc.so.6(+0x117160)[0x7f6a76969160]
/lib/x86_64-linux-gnu/libc.so.6(+0x1190a7)[0x7f6a7696b0a7]
/usr/local/lib/libtcl8.6.so(Tcl_CreateFileHandler+0xe5)[0x7f6a76d65d65]
/usr/local/lib/libtcl8.6.so(Tcl_OpenTcpServer+0x262)[0x7f6a76d63632]
/usr/local/lib/libtcl8.6.so(+0xf1f19)[0x7f6a76d0df19]
/usr/local/lib/libtcl8.6.so(TclNRRunCallbacks+0x47)[0x7f6a76c5e507]
/usr/local/lib/libtcl8.6.so(+0x128250)[0x7f6a76d44250]
/usr/local/lib/libtcl8.6.so(TclServiceIdle+0x46)[0x7f6a76d44ac6]
/usr/local/lib/libtcl8.6.so(Tcl_DoOneEvent+0x16d)[0x7f6a76d2433d]
/usr/local/lib/libtcl8.6.so(+0xcadb6)[0x7f6a76ce6db6]
/usr/local/lib/libtcl8.6.so(TclNRRunCallbacks+0x47)[0x7f6a76c5e507]
/usr/local/lib/libtcl8.6.so(+0x44575)[0x7f6a76c60575]
/usr/local/lib/libtcl8.6.so(Tcl_FSEvalFileEx+0x258)[0x7f6a76d16fb8]
/usr/local/lib/libtcl8.6.so(Tcl_MainEx+0x257)[0x7f6a76d1e837]
/usr/local/bin/tclsh8.6[0x4007f4]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf0)[0x7f6a76872830]
/usr/local/bin/tclsh8.6(_start+0x29)[0x400829]