From 619d98749292c53545d5ee3215cf8fae75cbfa88 Mon Sep 17 00:00:00 2001
From: Morilli <35152647+Morilli@users.noreply.github.com>
Date: Mon, 2 Jun 2025 21:24:38 +0200
Subject: [PATCH] fix possible out of bounds access due to unsanitized
 nSelectors usage

---
 src/SharpCompress/Compressors/BZip2/CBZip2InputStream.cs | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/SharpCompress/Compressors/BZip2/CBZip2InputStream.cs b/src/SharpCompress/Compressors/BZip2/CBZip2InputStream.cs
index a467942f..cf006dbc 100644
--- a/src/SharpCompress/Compressors/BZip2/CBZip2InputStream.cs
+++ b/src/SharpCompress/Compressors/BZip2/CBZip2InputStream.cs
@@ -542,9 +542,14 @@ internal class CBZip2InputStream : Stream
             {
                 j++;
             }
-            selectorMtf[i] = (char)j;
+            if (i < BZip2Constants.MAX_SELECTORS)
+            {
+                selectorMtf[i] = (char)j;
+            }
         }
 
+        nSelectors = Math.Min(nSelectors, BZip2Constants.MAX_SELECTORS);
+
         /* Undo the MTF values for the selectors. */
         {
             var pos = new char[BZip2Constants.N_GROUPS];