diff --git a/ChangeLog b/ChangeLog
index 4aa40cb..8148b74 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -33,6 +33,9 @@
    * Change default choice of DHE parameters from untrustworthy RFC 5114
      to RFC 3526 containing parameters generated in a nothing-up-my-sleeve
      manner.
+   * Fix a potential heap buffer overread in ALPN extension parsing
+     (server-side). Could result in application crash, but only if an ALPN
+     name larger than 16 bytes had been configured on the server.
 
 Features
    * Allow comments in test data files.
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index dd6397c..2200041 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -791,25 +791,33 @@
         return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO );
 
     /*
-     * Use our order of preference
+     * Validate peer's list (lengths)
      */
     start = buf + 2;
     end = buf + len;
+    for( theirs = start; theirs != end; theirs += cur_len )
+    {
+        cur_len = *theirs++;
+
+        /* Current identifier must fit in list */
+        if( cur_len > (size_t)( end - theirs ) )
+            return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO );
+
+        /* Empty strings MUST NOT be included */
+        if( cur_len == 0 )
+            return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO );
+    }
+
+    /*
+     * Use our order of preference
+     */
     for( ours = ssl->alpn_list; *ours != NULL; ours++ )
     {
         ours_len = strlen( *ours );
         for( theirs = start; theirs != end; theirs += cur_len )
         {
-            /* If the list is well formed, we should get equality first */
-            if( theirs > end )
-                return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO );
-
             cur_len = *theirs++;
 
-            /* Empty strings MUST NOT be included */
-            if( cur_len == 0 )
-                return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO );
-
             if( cur_len == ours_len &&
                 memcmp( theirs, *ours, cur_len ) == 0 )
             {