https://github.com/fribidi/fribidi/commit/034c6e9a1d296286305f4cfd1e0072b879f52568.patch

From 034c6e9a1d296286305f4cfd1e0072b879f52568 Mon Sep 17 00:00:00 2001
From: Dov Grobgeld <dov.grobgeld@gmail.com>
Date: Thu, 24 Oct 2019 09:37:29 +0300
Subject: [PATCH] Truncate isolate_level to FRIBIDI_BIDI_MAX_EXPLICIT_LEVEL

---
 lib/fribidi-bidi.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/fribidi-bidi.c b/lib/fribidi-bidi.c
index 6c84392..d384878 100644
--- a/lib/fribidi-bidi.c
+++ b/lib/fribidi-bidi.c
@@ -747,7 +747,9 @@ fribidi_get_par_embedding_levels_ex (
             }
 
 	  RL_LEVEL (pp) = level;
-          RL_ISOLATE_LEVEL (pp) = isolate_level++;
+          RL_ISOLATE_LEVEL (pp) = isolate_level;
+          if (isolate_level < FRIBIDI_BIDI_MAX_EXPLICIT_LEVEL-1)
+              isolate_level++;
           base_level_per_iso_level[isolate_level] = new_level;
 
 	  if (!FRIBIDI_IS_NEUTRAL (override))
