In libtirpc before 1.3.3rc1, remote attackers could exhaust the file descriptors of a process that uses libtirpc because idle TCP connections are mishandled. This can, in turn, lead to an svcrun infinite loop without accepting new connections.

Last updated 18 August 2025

A flaw was found in libtirpc. The return value of makefdxprt was used without checking for NULL in svcvc.c, leading to a null pointer dereference / segfault if the maximum number of available file descriptors was exhausted.

References: https://bugzilla.novell.com/showbug.cgi?id=968175

Upstream Patch: http://git.linux-nfs.org/?p=steved/libtirpc.git;a=commit;h=1c77f7a869bdea2a34799d774460d1f9983d45f0

The Nessus plugin for Sun RPC XDR xdrmemgetbytes Function Remote Overflow [1] causes rpcbind to crash due to freeing an invalid pointer.

glibc detected /sbin/rpcbind: free(): invalid pointer: 0xbf7f494c poll returned read fds < 6 > ======= Backtrace: ========= /lib/libc.so.6(-0xff84c1cf)[0x240e31] /lib/libtirpc.so.1(xdrbytes+0x9f)[0xb3ca9f] /sbin/rpcbind(+0x5714)[0x631714] /lib/libtirpc.so.1(+0x14ea4)[0xb36ea4] /lib/libtirpc.so.1(+0x14e6e)[0xb36e6e] /sbin/rpcbind(+0x591e)[0x63191e] /sbin/rpcbind(pmapservice+0x174)[0x6344e4] /lib/libtirpc.so.1(svcgetreqcommon+0x2ae)[0xb3600e] /lib/libtirpc.so.1(svcgetreqpoll+0x8f)[0xb360bf] /sbin/rpcbind(+0x509b)[0x63109b] /sbin/rpcbind(main+0x4dc)[0x62fd3c] /lib/libc.so.6(libcstartmain+0xe6)[0x1e6ce6] /sbin/rpcbind(+0x21c1)[0x62e1c1] ======= Memory map: ======== 001d0000-00360000 r-xp 00000000 08:03 131950 /lib/libc-2.12.so 00360000-00361000 ---p 00190000 08:03 131950 /lib/libc-2.12.so 00361000-00363000 r--p 00190000 08:03 131950 /lib/libc-2.12.so 00363000-00364000 rw-p 00192000 08:03 131950 /lib/libc-2.12.so 00364000-00367000 rw-p 00000000 00:00 0 0056e000-00585000 r-xp 00000000 08:03 137050 /lib/libnsl-2.12.so 00585000-00586000 r--p 00016000 08:03 137050 /lib/libnsl-2.12.so 00586000-00587000 rw-p 00017000 08:03 137050 /lib/libnsl-2.12.so 00587000-00589000 rw-p 00000000 00:00 0 0062c000-00639000 r-xp 00000000 08:03 394181 /sbin/rpcbind 00639000-0063a000 rw-p 0000d000 08:03 394181 /sbin/rpcbind 00688000-00690000 r-xp 00000000 08:03 137055 /lib/libwrap.so.0.7.6 00690000-00691000 r--p 00007000 08:03 137055 /lib/libwrap.so.0.7.6 00691000-00692000 rw-p 00008000 08:03 137055 /lib/libwrap.so.0.7.6 0076f000-00786000 r-xp 00000000 08:03 131977 /lib/libpthread-2.12.so 00786000-00787000 r--p 00016000 08:03 131977 /lib/libpthread-2.12.so 00787000-00788000 rw-p 00017000 08:03 131977 /lib/libpthread-2.12.so 00788000-0078a000 rw-p 00000000 00:00 0 008bb000-008bc000 r-xp 00000000 00:00 0 [vdso] 008ef000-008fb000 r-xp 00000000 08:03 137169 /lib/libnssfiles-2.12.so 008fb000-008fc000 r--p 0000b000 08:03 137169 /lib/libnssfiles-2.12.so 008fc000-008fd000 rw-p 0000c000 08:03 137169 /lib/libnssfiles-2.12.so 0099f000-009bd000 r-xp 00000000 08:03 131584 /lib/ld-2.12.so 009bd000-009be000 r--p 0001d000 08:03 131584 /lib/ld-2.12.so 009be000-009bf000 rw-p 0001e000 08:03 131584 /lib/ld-2.12.so 009d6000-009de000 r-xp 00000000 08:03 136753 /lib/libgssglue.so.1.0.0 009de000-009df000 rw-p 00007000 08:03 136753 /lib/libgssglue.so.1.0.0 00ad9000-00af6000 r-xp 00000000 08:03 136736 /lib/libgccs-4.4.7-20120601.so.1 00af6000-00af7000 rw-p 0001d000 08:03 136736 /lib/libgccs-4.4.7-20120601.so.1 00b22000-00b48000 r-xp 00000000 08:03 131852 /lib/libtirpc.so.1.0.10 00b48000-00b49000 rw-p 00026000 08:03 131852 /lib/libtirpc.so.1.0.10 00e35000-00e38000 r-xp 00000000 08:03 132420 /lib/libdl-2.12.so 00e38000-00e39000 r--p 00002000 08:03 132420 /lib/libdl-2.12.so 00e39000-00e3a000 rw-p 00003000 08:03 132420 /lib/libdl-2.12.so 014aa000-014cb000 rw-p 00000000 00:00 0 [heap] b770f000-b7712000 rw-p 00000000 00:00 0 b772d000-b7730000 rw-p 00000000 00:00 0 bf7e3000-bf808000 rw-p 00000000 00:00 0 [stack] rpcbind debugging enabled.

This is not the same flaw as CVE-2003-0028 (what the plugin was written for).

The above observed on a Red Hat Enterprise Linux 6 host.

[1] http://www.tenable.com/plugins/index.php?view=single&id=11420

An infinite loop vulnerability was found in libtirpc before version 1.0.2-rc2. With the port to using poll rather than select, exhaustion of file descriptors would cause the server to enter an infinite loop, consuming a large amount of CPU time and denying service to other clients until restarted.