Commit 6cefe9724 for imagemagick.org

commit 6cefe972445185cbb9c76651231d52512e0ec14b
Author: Dirk Lemstra <dirk@lemstra.org>
Date:   Sat Feb 28 11:01:24 2026 +0100

    Corrected typecast to avoid an out of bounds write (GHSA-r39q-jr8h-gcq2)

diff --git a/coders/sixel.c b/coders/sixel.c
index 5de968e35..a9ccd8a67 100644
--- a/coders/sixel.c
+++ b/coders/sixel.c
@@ -591,7 +591,7 @@ static MagickBooleanType sixel_decode(Image *image,unsigned char *p,
                             return(MagickFalse);
                           }
                         for (x = 0; x < repeat_count; x++)
-                          imbuf[(int) offset+x]=(sixel_pixel_t) color_index;
+                          imbuf[(size_t) offset+x]=(sixel_pixel_t) color_index;
                       }
                       if (max_x < (position_x+repeat_count-1))
                         max_x = position_x+repeat_count-1;