diff -up onig-6.8.2/src/regexec.c.orig onig-6.8.2/src/regexec.c
--- onig-6.8.2/src/regexec.c.orig	2018-04-17 02:08:37.000000000 +0200
+++ onig-6.8.2/src/regexec.c	2023-12-07 15:39:01.502781873 +0100
@@ -4384,14 +4384,14 @@ forward_search_range(regex_t* reg, const
 #endif
 
   p = s;
-  if (reg->dmin > 0) {
+  if (reg->dmin != 0) {
+    if (end - p <= reg->dmin)
+      return 0; /* fail */
     if (ONIGENC_IS_SINGLEBYTE(reg->enc)) {
       p += reg->dmin;
     }
     else {
       UChar *q = p + reg->dmin;
-
-      if (q >= end) return 0; /* fail */
       while (p < q) p += enclen(reg->enc, p);
     }
   }
@@ -4420,7 +4420,7 @@ forward_search_range(regex_t* reg, const
   }
 
   if (p && p < range) {
-    if (p - reg->dmin < s) {
+    if (p - s < reg->dmin) {
     retry_gate:
       pprev = p;
       p += enclen(reg->enc, p);
@@ -4468,6 +4468,7 @@ forward_search_range(regex_t* reg, const
           *low_prev = onigenc_get_prev_char_head(reg->enc,
                                                  (pprev ? pprev : str), p);
       }
+      *high = p;
     }
     else {
       if (reg->dmax != INFINITE_LEN) {
@@ -4492,9 +4493,12 @@ forward_search_range(regex_t* reg, const
           }
         }
       }
+      /* no needs to adjust *high, *high is used as range check only */
+      if (p - str < reg->dmin)
+        *high = (UChar* )str;
+      else
+        *high = p - reg->dmin;
     }
-    /* no needs to adjust *high, *high is used as range check only */
-    *high = p - reg->dmin;
 
 #ifdef ONIG_DEBUG_SEARCH
     fprintf(stderr,
@@ -4517,7 +4521,6 @@ backward_search_range(regex_t* reg, cons
 {
   UChar *p;
 
-  range += reg->dmin;
   p = s;
 
  retry:
@@ -4598,10 +4601,22 @@ backward_search_range(regex_t* reg, cons
       }
     }
 
-    /* no needs to adjust *high, *high is used as range check only */
     if (reg->dmax != INFINITE_LEN) {
-      *low  = p - reg->dmax;
-      *high = p - reg->dmin;
+      if (p - str < reg->dmax)
+        *low = (UChar* )str;
+      else
+        *low = p - reg->dmax;
+
+      if (reg->dmin != 0) {
+        if (p - str < reg->dmin)
+          *high = (UChar* )str;
+        else
+          *high = p - reg->dmin;
+      }
+      else {
+        *high = p;
+      }
+
       *high = onigenc_get_right_adjust_char_head(reg->enc, adjrange, *high);
     }
 
@@ -4731,13 +4746,16 @@ onig_search_with_param(regex_t* reg, con
         goto mismatch_no_msa;
 
       if (range > start) {
-        if ((OnigLen )(min_semi_end - start) > reg->anchor_dmax) {
+        if (min_semi_end - start > reg->anchor_dmax) {
           start = min_semi_end - reg->anchor_dmax;
           if (start < end)
             start = onigenc_get_right_adjust_char_head(reg->enc, str, start);
         }
-        if ((OnigLen )(max_semi_end - (range - 1)) < reg->anchor_dmin) {
-          range = max_semi_end - reg->anchor_dmin + 1;
+       if (max_semi_end - (range - 1) < reg->anchor_dmin) {
+          if (max_semi_end - str + 1 < reg->anchor_dmin)
+            goto mismatch_no_msa;
+          else
+            range = max_semi_end - reg->anchor_dmin + 1;
         }
 
         if (start > range) goto mismatch_no_msa;
@@ -4745,12 +4763,16 @@ onig_search_with_param(regex_t* reg, con
            Backward search is used. */
       }
       else {
-        if ((OnigLen )(min_semi_end - range) > reg->anchor_dmax) {
+        if (min_semi_end - range > reg->anchor_dmax) {
           range = min_semi_end - reg->anchor_dmax;
         }
-        if ((OnigLen )(max_semi_end - start) < reg->anchor_dmin) {
-          start = max_semi_end - reg->anchor_dmin;
-          start = ONIGENC_LEFT_ADJUST_CHAR_HEAD(reg->enc, str, start);
+        if (max_semi_end - start < reg->anchor_dmin) {
+           if (max_semi_end - str < reg->anchor_dmin)
+             goto mismatch_no_msa;
+           else {
+             start = max_semi_end - reg->anchor_dmin;
+             start = ONIGENC_LEFT_ADJUST_CHAR_HEAD(reg->enc, str, start);
+           }
         }
         if (range > start) goto mismatch_no_msa;
       }
@@ -4818,15 +4840,19 @@ onig_search_with_param(regex_t* reg, con
     if (reg->optimize != OPTIMIZE_NONE) {
       UChar *sch_range, *low, *high, *low_prev;
 
-      sch_range = (UChar* )range;
       if (reg->dmax != 0) {
         if (reg->dmax == INFINITE_LEN)
           sch_range = (UChar* )end;
         else {
-          sch_range += reg->dmax;
-          if (sch_range > end) sch_range = (UChar* )end;
+          if ((end - range) < reg->dmax)
+            sch_range = (UChar* )end;
+          else {
+            sch_range = (UChar* )range + reg->dmax;
+          }
         }
       }
+      else
+        sch_range = (UChar* )range;
 
       if ((end - start) < reg->threshold_len)
         goto mismatch;
@@ -4885,18 +4911,28 @@ onig_search_with_param(regex_t* reg, con
 
     if (reg->optimize != OPTIMIZE_NONE) {
       UChar *low, *high, *adjrange, *sch_start;
+      const UChar *min_range;
 
       if (range < end)
         adjrange = ONIGENC_LEFT_ADJUST_CHAR_HEAD(reg->enc, str, range);
       else
         adjrange = (UChar* )end;
 
+      if (end - range > reg->dmin)
+        min_range = range + reg->dmin;
+      else
+        min_range = end;
+
       if (reg->dmax != INFINITE_LEN &&
           (end - range) >= reg->threshold_len) {
         do {
-          sch_start = s + reg->dmax;
-          if (sch_start > end) sch_start = (UChar* )end;
-          if (backward_search_range(reg, str, end, sch_start, range, adjrange,
+          if (end - s > reg->dmax)
+            sch_start = s + reg->dmax;
+          else {
+            sch_start = (UChar* )end;
+          }
+
+          if (backward_search_range(reg, str, end, sch_start, min_range, adjrange,
                                     &low, &high) <= 0)
             goto mismatch;
 
@@ -4914,19 +4950,7 @@ onig_search_with_param(regex_t* reg, con
       else { /* check only. */
         if ((end - range) < reg->threshold_len) goto mismatch;
 
-        sch_start = s;
-        if (reg->dmax != 0) {
-          if (reg->dmax == INFINITE_LEN)
-            sch_start = (UChar* )end;
-          else {
-            sch_start += reg->dmax;
-            if (sch_start > end) sch_start = (UChar* )end;
-            else
-              sch_start = ONIGENC_LEFT_ADJUST_CHAR_HEAD(reg->enc,
-                                                        start, sch_start);
-          }
-        }
-        if (backward_search_range(reg, str, end, sch_start, range, adjrange,
+        if (backward_search_range(reg, str, end, sch_start, min_range, adjrange,
                                   &low, &high) <= 0) goto mismatch;
       }
     }