diff -Nrbu mailx-12.5/lzw.c mailx-12.5-OK/lzw.c
--- mailx-12.5/lzw.c	2006-03-04 03:32:16.000000000 +0300
+++ mailx-12.5-OK/lzw.c	2011-08-17 16:30:01.000000000 +0400
@@ -516,6 +516,8 @@
 
 		/* Generate output characters in reverse order. */
 		while (code >= 256) {
+			if (stackp - de_stack >= HSIZE - 1)
+				return -1;
 			*stackp++ = tab_suffixof(code);
 			code = tab_prefixof(code);
 		}