CVE-2025-55160

ImageMagick is free and open-source software used for editing and manipulating digital images. Prior to versions 6.9.13-27 and 7.1.2-1, there is undefined behavior (function-type-mismatch) in splay tree cloning callback. This results in a deterministic abort under UBSan (DoS in sanitizer builds), with no crash in a non-sanitized build. This issue has been patched in versions 6.9.13-27 and 7.1.2-1.

ImageMagick is free and open-source software used for editing and manipulating digital images. Prior to versions 6.9.13-27 and 7.1.2-1, there is undefined behavior (function-type-mismatch) in splay tree cloning callback. This results in a deterministic abort under UBSan (DoS in sanitizer builds), with no crash in a non-sanitized build. This issue has been patched in versions 6.9.13-27 and 7.1.2-1.

## Summary - **Target:** ImageMagick (commit `ecc9a5eb456747374bae8e07038ba10b3d8821b3`) - **Type:** Undefined Behavior (function-type-mismatch) in splay tree cloning callback - **Impact:** Deterministic abort under UBSan (DoS in sanitizer builds). No crash in a non-sanitized build; likely low security impact. - **Trigger:** Minimal **2-byte** input parsed via MagickWand, then coalescing. ## Environment OS: macOS (Apple Silicon/arm64) Homebrew clang version 20.1.8 Target: arm64-apple-darwin24.5.0 Thread model: posix InstalledDir: /opt/homebrew/Cellar/llvm/20.1.8/bin Configuration file: /opt/homebrew/etc/clang/arm64-apple-darwin24.cfg Homebrew ImageMagick: `magick -version` → `ImageMagick 7.1.2-0 Q16-HDRI aarch64` pkg-config: `MagickWand-7.Q16HDRI` version `7.1.2` Library configure flags (capsule build): ./configure --disable-shared --enable-static --without-modules --without-magick-plus-plus --disable-openmp --without-perl --without-x --with-png=yes --without-jpeg --without-tiff --without-xml --without-lqr --without-gslib Harness compile flags: -fsanitize=fuzzer,address,undefined -fno-omit-frame-pointer pkg-config cflags/libs supplied: -I<...>/include/ImageMagick-7 -DMAGICKCORE_HDRI_ENABLE=1 -DMAGICKCORE_QUANTUM_DEPTH=16 -DMAGICKCORE_CHANNEL_MASK_DEPTH=32 and linked against MagickWand-7.Q16HDRI and MagickCore-7.Q16HDRI Sanitizer runtime: ASan+UBSan defaults. Repro also with `UBSAN_OPTIONS=print_stacktrace=1:halt_on_error=1` ## PoC - **Bytes (hex):** `1c 02` - **Base64:** `HAI=` - **sha256 (optional):** <fill in> ## Reproduction Create PoC: `printf '\x1c\x02' > poc.bin` Option A: libFuzzer harness - Run once: `./harness_ImageMagick_... -runs=1 ./poc.bin` - Expected: UBSan aborts with function-type-mismatch at `MagickCore/splay-tree.c:372:43`. Option B: standalone reproducer (C) - Compile (ensure `PKG_CONFIG_PATH` points to your ImageMagick if needed): /opt/homebrew/opt/llvm/bin/clang -g -O1 -fsanitize=address,undefined $(/opt/homebrew/bin/pkg-config --cflags MagickWand-7.Q16HDRI) repro.c -o repro $(/opt/homebrew/bin/pkg-config --libs MagickWand-7.Q16HDRI) - Run: UBSAN_OPTIONS=print_stacktrace=1:halt_on_error=1 ./repro ./poc.bin Observed output (excerpt) MagickCore/splay-tree.c:372:43: runtime error: call to function ConstantString through pointer to incorrect function type 'void *(*)(void *)' string.c:680: note: ConstantString defined here #0 CloneSplayTree splay-tree.c:372 #1 CloneImageProfiles profile.c:159 #2 CloneImage image.c:832 #3 CoalesceImages layer.c:269 #4 MagickCoalesceImages magick-image.c:1665 #5 main repro.c:XX Root cause The splay tree clone callback expects a function pointer of type `void *(*)(void *)`. ConstantString has a different signature (`char *ConstantString(const char *)`). Calling through the mismatched function type is undefined behavior in C and triggers UBSan’s function-type-mismatch. The path is exercised during coalescing: CloneImage → CloneImageProfiles → CloneSplayTree. Scope Reproduces with a minimal, sanitizer-instrumented, PNG-enabled build and delegates disabled (policy.xml), suggesting the issue is in MagickCore rather than external delegates. Suggested fix (sketch) Use a wrapper that matches the expected callback prototype, or adjust the splay-tree callback typedef for const-correctness. For example: static void *CloneStringShim(const void *p) { return (void *) ConstantString((const char *) p); } /* When setting splay-tree clone_value, use CloneStringShim instead of ConstantString. */ Alternatively, update the clone callback typedefs to use const void* consistently (and return void*) and ensure callers pass a correctly typed wrapper. Artifacts Minimised PoC: attached (poc.bin, 2 bytes; base64 HAI=) Harness source and exact build command (attached) Full UBSan trace (attached) Commit SHA and configure flags (above) Credits Discovered by: Lumina Mescuwa Method: libFuzzer + UBSan Verification - UBSan build: Reproduces with `halt_on_error=1`; aborts at `MagickCore/splay-tree.c:372`. - Non-sanitized Homebrew build (macOS arm64, clang 20.1.8): No crash; repro completes silently.

## Summary - **Target:** ImageMagick (commit `ecc9a5eb456747374bae8e07038ba10b3d8821b3`) - **Type:** Undefined Behavior (function-type-mismatch) in splay tree cloning callback - **Impact:** Deterministic abort under UBSan (DoS in sanitizer builds). No crash in a non-sanitized build; likely low security impact. - **Trigger:** Minimal **2-byte** input parsed via MagickWand, then coalescing. ## Environment OS: macOS (Apple Silicon/arm64) Homebrew clang version 20.1.8 Target: arm64-apple-darwin24.5.0 Thread model: posix InstalledDir: /opt/homebrew/Cellar/llvm/20.1.8/bin Configuration file: /opt/homebrew/etc/clang/arm64-apple-darwin24.cfg Homebrew ImageMagick: `magick -version` → `ImageMagick 7.1.2-0 Q16-HDRI aarch64` pkg-config: `MagickWand-7.Q16HDRI` version `7.1.2` Library configure flags (capsule build): ./configure --disable-shared --enable-static --without-modules --without-magick-plus-plus --disable-openmp --without-perl --without-x --with-png=yes --without-jpeg --without-tiff --without-xml --without-lqr --without-gslib Harness compile flags: -fsanitize=fuzzer,address,undefined -fno-omit-frame-pointer pkg-config cflags/libs supplied: -I<...>/include/ImageMagick-7 -DMAGICKCORE_HDRI_ENABLE=1 -DMAGICKCORE_QUANTUM_DEPTH=16 -DMAGICKCORE_CHANNEL_MASK_DEPTH=32 and linked against MagickWand-7.Q16HDRI and MagickCore-7.Q16HDRI Sanitizer runtime: ASan+UBSan defaults. Repro also with `UBSAN_OPTIONS=print_stacktrace=1:halt_on_error=1` ## PoC - **Bytes (hex):** `1c 02` - **Base64:** `HAI=` - **sha256 (optional):** <fill in> ## Reproduction Create PoC: `printf '\x1c\x02' > poc.bin` Option A: libFuzzer harness - Run once: `./harness_ImageMagick_... -runs=1 ./poc.bin` - Expected: UBSan aborts with function-type-mismatch at `MagickCore/splay-tree.c:372:43`. Option B: standalone reproducer (C) - Compile (ensure `PKG_CONFIG_PATH` points to your ImageMagick if needed): /opt/homebrew/opt/llvm/bin/clang -g -O1 -fsanitize=address,undefined $(/opt/homebrew/bin/pkg-config --cflags MagickWand-7.Q16HDRI) repro.c -o repro $(/opt/homebrew/bin/pkg-config --libs MagickWand-7.Q16HDRI) - Run: UBSAN_OPTIONS=print_stacktrace=1:halt_on_error=1 ./repro ./poc.bin Observed output (excerpt) MagickCore/splay-tree.c:372:43: runtime error: call to function ConstantString through pointer to incorrect function type 'void *(*)(void *)' string.c:680: note: ConstantString defined here #0 CloneSplayTree splay-tree.c:372 #1 CloneImageProfiles profile.c:159 #2 CloneImage image.c:832 #3 CoalesceImages layer.c:269 #4 MagickCoalesceImages magick-image.c:1665 #5 main repro.c:XX Root cause The splay tree clone callback expects a function pointer of type `void *(*)(void *)`. ConstantString has a different signature (`char *ConstantString(const char *)`). Calling through the mismatched function type is undefined behavior in C and triggers UBSan’s function-type-mismatch. The path is exercised during coalescing: CloneImage → CloneImageProfiles → CloneSplayTree. Scope Reproduces with a minimal, sanitizer-instrumented, PNG-enabled build and delegates disabled (policy.xml), suggesting the issue is in MagickCore rather than external delegates. Suggested fix (sketch) Use a wrapper that matches the expected callback prototype, or adjust the splay-tree callback typedef for const-correctness. For example: static void *CloneStringShim(const void *p) { return (void *) ConstantString((const char *) p); } /* When setting splay-tree clone_value, use CloneStringShim instead of ConstantString. */ Alternatively, update the clone callback typedefs to use const void* consistently (and return void*) and ensure callers pass a correctly typed wrapper. Artifacts Minimised PoC: attached (poc.bin, 2 bytes; base64 HAI=) Harness source and exact build command (attached) Full UBSan trace (attached) Commit SHA and configure flags (above) Credits Discovered by: Lumina Mescuwa Method: libFuzzer + UBSan Verification - UBSan build: Reproduces with `halt_on_error=1`; aborts at `MagickCore/splay-tree.c:372`. - Non-sanitized Homebrew build (macOS arm64, clang 20.1.8): No crash; repro completes silently.

ImageMagick es un software gratuito y de código abierto que se utiliza para editar y manipular imágenes digitales. En versiones anteriores a la 6.9.13-27 y la 7.1.2-1, existía un comportamiento indefinido (desajuste de tipo de función) en la retrollamada de clonación del árbol de despliegue. Esto provocaba una interrupción determinista en UBSan (ataque de denegación de servicio en compilaciones depuradoras), sin fallos en compilaciones no depuradas. Este problema se ha corregido en las versiones 6.9.13-27 y 7.1.2-1.