{"id":"CVE-2025-62609","aliases":["GHSA-j842-xgm4-wf88","PYSEC-2025-139"],"url":"https://o3.security/vulnerability/CVE-2025-62609","summary":"MLX has Wild Pointer Dereference in load_gguf()","details":"## Summary\n\nSegmentation fault in `mlx::core::load_gguf()` when loading malicious GGUF files. Untrusted pointer from external gguflib library is dereferenced without validation, causing application crash.\n\nEnvironment:\n- OS: Ubuntu 20.04.6 LTS\n- Compiler: Clang 19.1.7\n\n## Vulnerability\n\n**Location**: `mlx/io/gguf.cpp`\n- Function `extract_tensor_data()` at lines 59-79\n- Vulnerable memcpy at lines 64-67\n- Called from `load_arrays()` at line 177\n\n**The Bug**:\n```cpp\nstd::tuple extract_tensor_data(gguf_tensor* tensor) {\n std::optional equivalent_dtype = gguf_type_to_dtype(tensor->type);\n if (equivalent_dtype.has_value()) {\n allocator::Buffer buffer = allocator::malloc(tensor->bsize);\n memcpy(\n buffer.raw_ptr(),\n tensor->weights_data, // untrusted pointer from gguflib\n tensor->num_weights * equivalent_dtype.value().size());\n return {buffer, equivalent_dtype.value()};\n }\n // ...\n}\n```\n\n## Possible Fix\n\n```cpp\nstd::tuple extract_tensor_data(gguf_tensor* tensor) {\n std::optional equivalent_dtype = gguf_type_to_dtype(tensor->type);\n if (equivalent_dtype.has_value()) {\n // FIX: Validate pointer\n if (!tensor->weights_data) {\n throw std::runtime_error(\"[load_gguf] NULL tensor data pointer\");\n }\n\n allocator::Buffer buffer = allocator::malloc(tensor->bsize);\n memcpy(\n buffer.raw_ptr(),\n tensor->weights_data,\n tensor->num_weights * equivalent_dtype.value().size());\n return {buffer, equivalent_dtype.value()};\n }\n // ...\n}\n```\n\n## PoC\n\n```bash\n# Install MLX\npip install mlx\n\npython3 -c \"import mlx.core as mx; mx.load('exploit.gguf', format='gguf')\"\n```\n\nDownload the poc file [there](https://drive.google.com/file/d/1t9Z2RJGn-oHmluKWebU077UWSMGXeuVp/view?usp=sharing), or let me know how I can send it to you.\n\n**AddressSanitizer Output (with instrumented build)**:\n```\nAddressSanitizer:DEADLYSIGNAL\n=================================================================\n==5855==ERROR: AddressSanitizer: SEGV on unknown address 0x7fc432f64bc0 (pc 0x7fc430841c12 bp 0x7ffc04847ab0 sp 0x7ffc04847268 T0)\n==5855==The signal is caused by a READ memory access.\n #0 0x7fc430841c12 /build/glibc-B3wQXB/glibc-2.31/string/../sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S:312\n #1 0x55aac829756b in __asan_memcpy (/home/user1/mlx/fuzz/load_gguf/fuzz_load_gguf+0x9ef56b) (BuildId: 57467f1ce96052757daeef4b04739be7f23c5f1f)\n #2 0x55aacaa6e8dc in mlx::core::extract_tensor_data(gguf_tensor*) /home/user1/mlx/mlx/io/gguf.cpp:64:5\n #3 0x55aacaa773fc in mlx::core::load_arrays[abi:cxx11](gguf_ctx*) /home/user1/mlx/mlx/io/gguf.cpp:226:35\n #4 0x55aacaa782a9 in mlx::core::load_gguf(std::__cxx11::basic_string, std::allocator> const&, std::variant) /home/user1/mlx/mlx/io/gguf.cpp:250:17\n #5 0x55aac82dc696 in LLVMFuzzerTestOneInput /home/user1/mlx/fuzz/load_gguf/fuzz_load_gguf.cpp:49:19\n #6 0x55aac81e25c6 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) (/home/user1/mlx/fuzz/load_gguf/fuzz_load_gguf+0x93a5c6) (BuildId: 57467f1ce96052757daeef4b04739be7f23c5f1f)\n #7 0x55aac81cc738 in fuzzer::RunOneTest(fuzzer::Fuzzer*, char const*, unsigned long) (/home/user1/mlx/fuzz/load_gguf/fuzz_load_gguf+0x924738) (BuildId: 57467f1ce96052757daeef4b04739be7f23c5f1f)\n #8 0x55aac81d220a in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) (/home/user1/mlx/fuzz/load_gguf/fuzz_load_gguf+0x92a20a) (BuildId: 57467f1ce96052757daeef4b04739be7f23c5f1f)\n #9 0x55aac81fbb82 in main (/home/user1/mlx/fuzz/load_gguf/fuzz_load_gguf+0x953b82) (BuildId: 57467f1ce96052757daeef4b04739be7f23c5f1f)\n #10 0x7fc4307aa082 in __libc_start_main /build/glibc-B3wQXB/glibc-2.31/csu/../csu/libc-start.c:308:16\n #11 0x55aac81c73ed in _start (/home/user1/mlx/fuzz/load_gguf/fuzz_load_gguf+0x91f3ed) (BuildId: 57467f1ce96052757daeef4b04739be7f23c5f1f)\n\n==5855==Register values:\nrax = 0x0000502000000098 rbx = 0xfafafafa0000fa00 rcx = 0x00000a047fff8013 rdx = 0x0000000000000008\nrdi = 0x0000502000000098 rsi = 0x00007fc432f64bc0 rbp = 0x00007ffc04847ab0 rsp = 0x00007ffc04847268\n r8 = 0x00000a0400000013 r9 = 0x0000000000000000 r10 = 0x00000a0400000013 r11 = 0x0000000000000000\nr12 = 0x00000a047fff8010 r13 = 0xffffffffffffffc7 r14 = 0x00007fc42dd00280 r15 = 0x00000ff885ba0050\nAddressSanitizer can not provide additional info.\nSUMMARY: AddressSanitizer: SEGV /build/glibc-B3wQXB/glibc-2.31/string/../sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S:312\n==5855==ABORTING\n```\n\n## Impact\n\n- **Attack vector**: Malicious GGUF file (model weights, typically from untrusted sources)\n- **Affects**: MLX users on all platforms who call the vulnerable method with unsanitized input.\n- **Result**: Segmentation fault (uncatchable by exception handlers)\n\n---\nCredits:\n\n- Markiyan Melnyk (ARIMLABS)\n- Mykyta Mudryi (ARIMLABS)\n- Markiyan Chaklosh (ARIMLABS)","published":"2025-11-21T18:57:45.930Z","modified":"2026-08-12T03:51:48.391810714Z","cvss":null,"epss":{"score":0.00379,"percentile":0.31557,"asOf":"2026-09-16"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"mlx","fixedVersion":"0.29.4"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/62xxx/CVE-2025-62609.json"},{"type":"ADVISORY","url":"https://github.com/ml-explore/mlx/security/advisories/GHSA-j842-xgm4-wf88"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-62609"},{"type":"PACKAGE","url":"https://github.com/ml-explore/mlx"},{"type":"WEB","url":"https://github.com/pypa/advisory-database/tree/main/vulns/mlx/PYSEC-2025-139.yaml"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:48.391810714Z"}}