diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1b9341d6..b3a89c8d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -19,6 +19,7 @@ Until May 2022 (inclusive) no changelog was kept. We might try to reconstruct it
 
 ### Changed
 
+* CMake: Update to v4.2.3
 * python: Require at least 3.12.12 in prefer_system_check
 * ROOT: Update to 6.36.08
 * defaults-actstracking: Removed all overrides unrelated to ACTS or C++20.
diff --git a/cmake.sh b/cmake.sh
index fc7d752c..95fa2e12 100644
--- a/cmake.sh
+++ b/cmake.sh
@@ -1,9 +1,9 @@
 package: CMake
 version: "%(tag_basename)s"
-tag: "v3.26.5"
+tag: "v4.2.3"
 source: https://github.com/Kitware/CMake
 build_requires:
- - "GCC-Toolchain:(?!osx)"
+  - "GCC-Toolchain:(?!osx)"
 prefer_system: .*
 prefer_system_check: |
     REQUESTED_VERSION=${REQUESTED_VERSION#v}
@@ -12,27 +12,27 @@ prefer_system_check: |
 ---
 #!/bin/bash -e
 
-cat > build-flags.cmake <<- EOF
-# Disable Java capabilities; we don't need it and on OS X might miss the
-# required /System/Library/Frameworks/JavaVM.framework/Headers/jni.h.
-SET(JNI_H FALSE CACHE BOOL "" FORCE)
-SET(Java_JAVA_EXECUTABLE FALSE CACHE BOOL "" FORCE)
-SET(Java_JAVAC_EXECUTABLE FALSE CACHE BOOL "" FORCE)
+cat >build-flags.cmake <<-EOF
+	# Disable Java capabilities; we don't need it and on OS X might miss the
+	# required /System/Library/Frameworks/JavaVM.framework/Headers/jni.h.
+	SET(JNI_H FALSE CACHE BOOL "" FORCE)
+	SET(Java_JAVA_EXECUTABLE FALSE CACHE BOOL "" FORCE)
+	SET(Java_JAVAC_EXECUTABLE FALSE CACHE BOOL "" FORCE)
 
-# SL6 with GCC 4.6.1 and LTO requires -ltinfo with -lcurses for link to succeed,
-# but cmake is not smart enough to find it. We do not really need ccmake anyway,
-# so just disable it.
-SET(BUILD_CursesDialog FALSE CACHE BOOL "" FORCE)
+	# SL6 with GCC 4.6.1 and LTO requires -ltinfo with -lcurses for link to succeed,
+	# but cmake is not smart enough to find it. We do not really need ccmake anyway,
+	# so just disable it.
+	SET(BUILD_CursesDialog FALSE CACHE BOOL "" FORCE)
 EOF
 
 $SOURCEDIR/bootstrap --prefix=$INSTALLROOT \
-                     --init=build-flags.cmake \
-                     ${JOBS:+--parallel=$JOBS}
+	--init=build-flags.cmake \
+	${JOBS:+--parallel=$JOBS}
 make ${JOBS+-j $JOBS}
 make install/strip
 
 mkdir -p etc/modulefiles
-cat > etc/modulefiles/$PKGNAME <<EoF
+cat >etc/modulefiles/$PKGNAME <<EoF
 #%Module1.0
 proc ModulesHelp { } {
   global version
diff --git a/hepmc.sh b/hepmc.sh
index 28fdc6cd..1460aeca 100644
--- a/hepmc.sh
+++ b/hepmc.sh
@@ -25,6 +25,7 @@ cmake  $SOURCEDIR                           \
        -Dmomentum=GEV                       \
        -Dlength=MM                          \
        -Dbuild_docs:BOOL=OFF                \
+       -DCMAKE_POLICY_VERSION_MINIMUM=3.5 \
        -DCMAKE_INSTALL_PREFIX=$INSTALLROOT
 
 make ${JOBS+-j $JOBS}
diff --git a/pythia6.sh b/pythia6.sh
index 9fe0d6b2..afad261d 100644
--- a/pythia6.sh
+++ b/pythia6.sh
@@ -16,6 +16,7 @@ build_requires:
 cmake ${SOURCEDIR}                           \
       -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE} \
       -DCMAKE_INSTALL_PREFIX=${INSTALLROOT}  \
+      -DCMAKE_POLICY_VERSION_MINIMUM=3.5 \
       -DCMAKE_INSTALL_LIBDIR=lib
 make ${JOBS+-j$JOBS}
 make install
diff --git a/tbb.sh b/tbb.sh
index 3a7ae649..bf1f4c53 100644
--- a/tbb.sh
+++ b/tbb.sh
@@ -22,6 +22,7 @@ prepend_path:
 cmake "$SOURCEDIR" -DCMAKE_INSTALL_PREFIX="$INSTALLROOT" \
           ${CXXSTD:+-DCMAKE_CXX_STANDARD=$CXXSTD} \
           -DCMAKE_INSTALL_LIBDIR=lib \
+	  -DCMAKE_POLICY_VERSION_MINIMUM=3.5 \
 	  -DTBB_TEST=OFF
 
 # Build and install
diff --git a/yaml-cpp.sh b/yaml-cpp.sh
index ea9fc427..f5b45fd3 100644
--- a/yaml-cpp.sh
+++ b/yaml-cpp.sh
@@ -24,6 +24,7 @@ cmake $SOURCEDIR                                         \
   ${BOOST_ROOT:+-DBoost_INCLUDE_DIR:PATH="$BOOST_ROOT/include"}  \
   -DCMAKE_SKIP_RPATH=YES                                 \
   -DYAML_CPP_BUILD_TESTS=NO                              \
+  -DCMAKE_POLICY_VERSION_MINIMUM=3.5 \
   -DSKIP_INSTALL_FILES=1
 
 make ${JOBS+-j $JOBS} install