diff -urN ../exim-4.96.2.orig/src/lookups/dnsdb.c ./src/lookups/dnsdb.c
--- ../exim-4.96.2.orig/src/lookups/dnsdb.c	2023-10-15 00:55:23.000000000 +0300
+++ ./src/lookups/dnsdb.c	2023-11-17 20:33:11.371092000 +0200
@@ -412,7 +412,7 @@
           while (data_offset < rr->size)
             {
             uschar chunk_len = (rr->data)[data_offset];
-	    int remain = rr->size - data_offset;
+	    int remain = rr->size - data_offset - 1;
 
 	    /* Apparently there are resolvers that do not check RRs before passing
 	    them on, and glibc fails to do so.  So every application must...
@@ -423,7 +423,7 @@
 
             if (*outsep2  && data_offset != 0)
               yield = string_catn(yield, outsep2, 1);
-            yield = string_catn(yield, US ((rr->data) + ++data_offset), --chunk_len);
+            yield = string_catn(yield, US ((rr->data) + ++data_offset), chunk_len);
             data_offset += chunk_len;
             }
           }