CVE-2025-62609: Mlx MLX Has Wild Pointer Dereference Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-j842-xgm4-wf88",
  "modified" : "2026-06-06T00:34:04Z",
  "published" : "2025-11-21T18:03:20Z",
  "aliases" : [ "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<allocator::Buffer, Dtype> extract_tensor_data(gguf_tensor* tensor) {\n  std::optional<Dtype> 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<allocator::Buffer, Dtype> extract_tensor_data(gguf_tensor* tensor) {\n  std::optional<Dtype> 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<char, std::char_traits<char>, std::allocator<char>> const&, std::variant<std::monostate, mlx::core::Stream, mlx::core::Device>) /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)",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "mlx"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.29.4"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.29.3"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "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"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-476" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-11-21T18:03:20Z",
    "nvd_published_at" : "2025-11-21T19:16:02Z"
  }
}