diff --git a/.github/workflows/ubuntu.yml b/.github/workflows/ubuntu.yml
index 39098e4d7..7ae132d25 100644
--- a/.github/workflows/ubuntu.yml
+++ b/.github/workflows/ubuntu.yml
@@ -12,7 +12,7 @@ on:
 jobs:
   ci_test_clang:
     runs-on: ubuntu-latest
-    container: ghcr.io/nlohmann/json-ci:v2.3.0
+    container: ghcr.io/nlohmann/json-ci:v2.4.0
     steps:
       - uses: actions/checkout@v3
       - name: cmake
@@ -22,7 +22,7 @@ jobs:
 
   ci_test_gcc:
     runs-on: ubuntu-latest
-    container: ghcr.io/nlohmann/json-ci:v2.3.0
+    container: ghcr.io/nlohmann/json-ci:v2.4.0
     steps:
       - uses: actions/checkout@v3
       - name: cmake
@@ -32,7 +32,7 @@ jobs:
 
   ci_static_analysis:
     runs-on: ubuntu-latest
-    container: ghcr.io/nlohmann/json-ci:v2.3.0
+    container: ghcr.io/nlohmann/json-ci:v2.4.0
     strategy:
       matrix:
         target: [ci_clang_tidy, ci_cppcheck, ci_test_valgrind, ci_test_clang_sanitizer, ci_test_amalgamation, ci_clang_analyze, ci_cpplint, ci_cmake_flags, ci_single_binaries, ci_reproducible_tests, ci_non_git_tests, ci_offline_testdata, ci_infer]
@@ -45,7 +45,7 @@ jobs:
 
   ci_cmake_options:
     runs-on: ubuntu-latest
-    container: ghcr.io/nlohmann/json-ci:v2.3.0
+    container: ghcr.io/nlohmann/json-ci:v2.4.0
     strategy:
       matrix:
         target: [ci_test_diagnostics, ci_test_noexceptions, ci_test_noimplicitconversions, ci_test_legacycomparison]
@@ -58,7 +58,7 @@ jobs:
 
   ci_test_coverage:
     runs-on: ubuntu-latest
-    container: ghcr.io/nlohmann/json-ci:v2.3.0
+    container: ghcr.io/nlohmann/json-ci:v2.4.0
     steps:
       - uses: actions/checkout@v3
       - name: cmake
@@ -78,7 +78,7 @@ jobs:
 
   ci_test_compilers:
     runs-on: ubuntu-latest
-    container: ghcr.io/nlohmann/json-ci:v2.3.0
+    container: ghcr.io/nlohmann/json-ci:v2.4.0
     strategy:
       matrix:
         compiler: [g++-4.8, g++-4.9, g++-5, g++-6, g++-7, g++-8, g++-9, g++-10, clang++-3.5, clang++-3.6, clang++-3.7, clang++-3.8, clang++-3.9, clang++-4.0, clang++-5.0, clang++-6.0, clang++-7, clang++-8, clang++-9, clang++-10, clang++-11, clang++-12, clang++-13, clang++-14]
@@ -91,7 +91,7 @@ jobs:
 
   ci_test_standards:
     runs-on: ubuntu-latest
-    container: ghcr.io/nlohmann/json-ci:v2.3.0
+    container: ghcr.io/nlohmann/json-ci:v2.4.0
     strategy:
       matrix:
         standard: [11, 14, 17, 20]
@@ -105,7 +105,7 @@ jobs:
 
   ci_cuda_example:
     runs-on: ubuntu-latest
-    container: ghcr.io/nlohmann/json-ci:v2.3.0
+    container: ghcr.io/nlohmann/json-ci:v2.4.0
     steps:
       - uses: actions/checkout@v3
       - name: cmake
diff --git a/cmake/ci.cmake b/cmake/ci.cmake
index a571c493b..c30caade5 100644
--- a/cmake/ci.cmake
+++ b/cmake/ci.cmake
@@ -111,7 +111,7 @@ set(CLANG_CXXFLAGS
     -Wno-reserved-identifier
 )
 
-# Warning flags determined for GCC 12.0 (experimental) with https://github.com/nlohmann/gcc_flags:
+# Warning flags determined for GCC 13.0 (experimental) with https://github.com/nlohmann/gcc_flags:
 # Ignored GCC warnings:
 # -Wno-abi-tag                    We do not care about ABI tags.
 # -Wno-aggregate-return           The library uses aggregate returns.
@@ -161,6 +161,10 @@ set(GCC_CXXFLAGS
     -Wanalyzer-use-after-free
     -Wanalyzer-use-of-pointer-in-stale-stack-frame
     -Wanalyzer-use-of-uninitialized-value
+    -Wanalyzer-va-arg-type-mismatch
+    -Wanalyzer-va-list-exhausted
+    -Wanalyzer-va-list-leak
+    -Wanalyzer-va-list-use-after-va-end
     -Wanalyzer-write-to-const
     -Wanalyzer-write-to-string-literal
     -Warith-conversion
@@ -209,6 +213,7 @@ set(GCC_CXXFLAGS
     -Wctad-maybe-unsupported
     -Wctor-dtor-privacy
     -Wdangling-else
+    -Wdangling-pointer=2
     -Wdate-time
     -Wdelete-incomplete
     -Wdelete-non-virtual-dtor
@@ -279,6 +284,7 @@ set(GCC_CXXFLAGS
     -Wmissing-include-dirs
     -Wmissing-profile
     -Wmissing-requires
+    -Wmissing-template-keyword
     -Wmultichar
     -Wmultiple-inheritance
     -Wmultistatement-macros
@@ -343,6 +349,8 @@ set(GCC_CXXFLAGS
     -Wstrict-aliasing
     -Wstrict-aliasing=3
     -Wstrict-null-sentinel
+    -Wstrict-overflow
+    -Wstrict-overflow=5
     -Wstring-compare
     -Wstringop-overflow=4
     -Wstringop-overread
@@ -371,6 +379,7 @@ set(GCC_CXXFLAGS
     -Wterminate
     -Wtrampolines
     -Wtrigraphs
+    -Wtrivial-auto-var-init
     -Wtsan
     -Wtype-limits
     -Wundef
@@ -390,6 +399,8 @@ set(GCC_CXXFLAGS
     -Wunused-result
     -Wunused-value
     -Wunused-variable
+    -Wuse-after-free
+    -Wuse-after-free=3
     -Wuseless-cast
     -Wvarargs
     -Wvariadic-macros