diff --git a/ExternData/Resources/C-Sources/expat/README.md b/ExternData/Resources/C-Sources/expat/README.md
index fc0c9f7..d1e4a4a 100644
--- a/ExternData/Resources/C-Sources/expat/README.md
+++ b/ExternData/Resources/C-Sources/expat/README.md
@@ -1,4 +1,4 @@
-# Expat, Release 2.6.2
+# Expat, Release 2.6.3
 
 This is Expat, a C99 library for parsing
 [XML 1.0 Fourth Edition](https://www.w3.org/TR/2006/REC-xml-20060816/), started by
@@ -13,7 +13,7 @@ Expat supports the following compilers:
 
 - GNU GCC >=4.5
 - LLVM Clang >=3.5
-- Microsoft Visual Studio >=15.0/2017 (rolling `${today} minus 5 years`)
+- Microsoft Visual Studio >=16.0/2019 (rolling `${today} minus 5 years`)
 
 Windows users can use the
 [`expat-win32bin-*.*.*.{exe,zip}` download](https://github.com/libexpat/libexpat/releases),
@@ -151,10 +151,10 @@ support this mode of compilation (yet):
 
 1. Mass-patch `Makefile.am` files to use `libexpatw.la` for a library name:
    <br/>
-   `find -name Makefile.am -exec sed
+   `find . -name Makefile.am -exec sed
        -e 's,libexpat\.la,libexpatw.la,'
        -e 's,libexpat_la,libexpatw_la,'
-       -i {} +`
+       -i.bak {} +`
 
 1. Run `automake` to re-write `Makefile.in` files:<br/>
    `automake`
diff --git a/ExternData/Resources/C-Sources/expat/lib/expat.h b/ExternData/Resources/C-Sources/expat/lib/expat.h
index c2770be..d0d6015 100644
--- a/ExternData/Resources/C-Sources/expat/lib/expat.h
+++ b/ExternData/Resources/C-Sources/expat/lib/expat.h
@@ -1066,7 +1066,7 @@ XML_SetReparseDeferralEnabled(XML_Parser parser, XML_Bool enabled);
 */
 #define XML_MAJOR_VERSION 2
 #define XML_MINOR_VERSION 6
-#define XML_MICRO_VERSION 2
+#define XML_MICRO_VERSION 3
 
 #ifdef __cplusplus
 }
diff --git a/ExternData/Resources/C-Sources/expat/lib/siphash.h b/ExternData/Resources/C-Sources/expat/lib/siphash.h
index a1ed99e..04f6f74 100644
--- a/ExternData/Resources/C-Sources/expat/lib/siphash.h
+++ b/ExternData/Resources/C-Sources/expat/lib/siphash.h
@@ -126,8 +126,7 @@
    | ((uint64_t)((p)[4]) << 32) | ((uint64_t)((p)[5]) << 40)                   \
    | ((uint64_t)((p)[6]) << 48) | ((uint64_t)((p)[7]) << 56))
 
-#define SIPHASH_INITIALIZER                                                    \
-  { 0, 0, 0, 0, {0}, 0, 0 }
+#define SIPHASH_INITIALIZER {0, 0, 0, 0, {0}, 0, 0}
 
 struct siphash {
   uint64_t v0, v1, v2, v3;
diff --git a/ExternData/Resources/C-Sources/expat/lib/xmlparse.c b/ExternData/Resources/C-Sources/expat/lib/xmlparse.c
index 9966f61..0026842 100644
--- a/ExternData/Resources/C-Sources/expat/lib/xmlparse.c
+++ b/ExternData/Resources/C-Sources/expat/lib/xmlparse.c
@@ -1,4 +1,4 @@
-/* 2a14271ad4d35e82bde8ba210b4edb7998794bcbae54deab114046a300f9639a (2.6.2+)
+/* ba4cdf9bdb534f355a9def4c9e25d20ee8e72f95b0a4d930be52e563f5080196 (2.6.3+)
                             __  __            _
                          ___\ \/ /_ __   __ _| |_
                         / _ \\  /| '_ \ / _` | __|
@@ -39,6 +39,7 @@
    Copyright (c) 2022      Sean McBride <sean@rogue-research.com>
    Copyright (c) 2023      Owain Davies <owaind@bath.edu>
    Copyright (c) 2023-2024 Sony Corporation / Snild Dolkow <snild@sony.com>
+   Copyright (c) 2024      Berkay Eren Ürün <berkay.ueruen@siemens.com>
    Licensed under the MIT license:
 
    Permission is  hereby granted,  free of charge,  to any  person obtaining
@@ -306,7 +307,7 @@ typedef struct {
    The name of the element is stored in both the document and API
    encodings.  The memory buffer 'buf' is a separately-allocated
    memory area which stores the name.  During the XML_Parse()/
-   XMLParseBuffer() when the element is open, the memory for the 'raw'
+   XML_ParseBuffer() when the element is open, the memory for the 'raw'
    version of the name (in the document encoding) is shared with the
    document buffer.  If the element is open across calls to
    XML_Parse()/XML_ParseBuffer(), the buffer is re-allocated to
@@ -2056,6 +2057,12 @@ XML_ParseBuffer(XML_Parser parser, int len, int isFinal) {
 
   if (parser == NULL)
     return XML_STATUS_ERROR;
+
+  if (len < 0) {
+    parser->m_errorCode = XML_ERROR_INVALID_ARGUMENT;
+    return XML_STATUS_ERROR;
+  }
+
   switch (parser->m_parsingStatus.parsing) {
   case XML_SUSPENDED:
     parser->m_errorCode = XML_ERROR_SUSPENDED;
@@ -5875,11 +5882,11 @@ processInternalEntity(XML_Parser parser, ENTITY *entity, XML_Bool betweenDecl) {
     result = doProlog(parser, parser->m_internalEncoding, textStart, textEnd,
                       tok, next, &next, XML_FALSE, XML_FALSE,
                       XML_ACCOUNT_ENTITY_EXPANSION);
-  } else
-#endif /* XML_DTD */
+  } else {
     result = doContent(parser, parser->m_tagLevel, parser->m_internalEncoding,
                        textStart, textEnd, &next, XML_FALSE,
                        XML_ACCOUNT_ENTITY_EXPANSION);
+  }
 
   if (result == XML_ERROR_NONE) {
     if (textEnd != next && parser->m_parsingStatus.parsing == XML_SUSPENDED) {
@@ -5916,18 +5923,17 @@ internalEntityProcessor(XML_Parser parser, const char *s, const char *end,
   /* Set a safe default value in case 'next' does not get set */
   next = textStart;
 
-#ifdef XML_DTD
   if (entity->is_param) {
     int tok
         = XmlPrologTok(parser->m_internalEncoding, textStart, textEnd, &next);
     result = doProlog(parser, parser->m_internalEncoding, textStart, textEnd,
                       tok, next, &next, XML_FALSE, XML_TRUE,
                       XML_ACCOUNT_ENTITY_EXPANSION);
-  } else
-#endif /* XML_DTD */
+  } else {
     result = doContent(parser, openEntity->startTagLevel,
                        parser->m_internalEncoding, textStart, textEnd, &next,
                        XML_FALSE, XML_ACCOUNT_ENTITY_EXPANSION);
+  }
 
   if (result != XML_ERROR_NONE)
     return result;
@@ -5954,7 +5960,6 @@ internalEntityProcessor(XML_Parser parser, const char *s, const char *end,
     return XML_ERROR_NONE;
   }
 
-#ifdef XML_DTD
   if (entity->is_param) {
     int tok;
     parser->m_processor = prologProcessor;
@@ -5962,9 +5967,7 @@ internalEntityProcessor(XML_Parser parser, const char *s, const char *end,
     return doProlog(parser, parser->m_encoding, s, end, tok, next, nextPtr,
                     (XML_Bool)! parser->m_parsingStatus.finalBuffer, XML_TRUE,
                     XML_ACCOUNT_DIRECT);
-  } else
-#endif /* XML_DTD */
-  {
+  } else {
     parser->m_processor = contentProcessor;
     /* see externalEntityContentProcessor vs contentProcessor */
     result = doContent(parser, parser->m_parentParser ? 1 : 0,
@@ -7041,6 +7044,16 @@ dtdCopy(XML_Parser oldParser, DTD *newDtd, const DTD *oldDtd,
     if (! newE)
       return 0;
     if (oldE->nDefaultAtts) {
+      /* Detect and prevent integer overflow.
+       * The preprocessor guard addresses the "always false" warning
+       * from -Wtype-limits on platforms where
+       * sizeof(int) < sizeof(size_t), e.g. on x86_64. */
+#if UINT_MAX >= SIZE_MAX
+      if ((size_t)oldE->nDefaultAtts
+          > ((size_t)(-1) / sizeof(DEFAULT_ATTRIBUTE))) {
+        return 0;
+      }
+#endif
       newE->defaultAtts
           = ms->malloc_fcn(oldE->nDefaultAtts * sizeof(DEFAULT_ATTRIBUTE));
       if (! newE->defaultAtts) {
@@ -7585,6 +7598,15 @@ nextScaffoldPart(XML_Parser parser) {
   int next;
 
   if (! dtd->scaffIndex) {
+    /* Detect and prevent integer overflow.
+     * The preprocessor guard addresses the "always false" warning
+     * from -Wtype-limits on platforms where
+     * sizeof(unsigned int) < sizeof(size_t), e.g. on x86_64. */
+#if UINT_MAX >= SIZE_MAX
+    if (parser->m_groupSize > ((size_t)(-1) / sizeof(int))) {
+      return -1;
+    }
+#endif
     dtd->scaffIndex = (int *)MALLOC(parser, parser->m_groupSize * sizeof(int));
     if (! dtd->scaffIndex)
       return -1;