# Duplicate Check - HDF5 vlen attribute/global heap hang

Date: 2026-06-24 UTC / 2026-06-25 Asia/Ho_Chi_Minh

## Local Submitted-Report Denylist

Source:

- `/home/hacnho/Projects/research/huntr_mysubmission.html`
- Parsed denylist: `targets/huntr/evidence/dashboard-dupcheck-20260624/huntr-submissions-denylist-latest.json`

Matched adjacent entries only:

- `HDF5 Fletcher32 filter SIGSEGV on single-byte malformed chunked dataset in HDF5`
- `Pickle scanner bypass via h5py File.create_dataset writes attacker-controlled HDF5 files while picklescan and modelscan report clean in Pickle`

Verdict: not a local duplicate. This candidate is a native HDF5 root attribute/global heap hang with `fletcher32=False`, not Fletcher32 and not pickle.

## Huntr Hacktivity Title Filter

Script:

```bash
python3 targets/huntr/poc/tflite-litert-lab/huntr_hacktivity_title_filter.py \
  --out-dir targets/huntr/evidence/hdf5-non-fletcher-lab \
  --terms H5HG H5Aread "global heap" "HDF5 attribute" "HDF5 vlen" \
  --max-clicks 0 --click-delay-ms 500
```

Result file:

- `targets/huntr/evidence/hdf5-non-fletcher-lab/hacktivity-title-filter-results-2026-06-23.json`

All terms returned `link_count: 0` for the first 100 scanned reports.

## Public Prior Art

Adjacent but not the same:

- HDFGroup issue `hdf5#2662`: historical `h5diff` SIGSEGV in HDF5 1.14.0 around vlen attributes/global heap. This candidate reproduces on HDF5 2.1.0, affects `h5dump -A` and h5py root attribute reads, and manifests as a hang.
- CVE-2024-29160: older heap overflow in `H5HG__cache_heap_deserialize` through HDF5 1.14.3. This candidate affects HDF5 2.1.0 and is an unbounded hang.
- Huntr/Vulners `Integer Overflow Bypasses Memory Safety Checks in H5 Dataset Loading`: Keras/H5 dataset loading, not root vlen attributes/global heap.
- Keras/HDF5 external-link and external-storage reports: different surface; this PoC uses no external links/storage.

Verdict: candidate NOVEL, with adjacent global-heap/vlen prior disclosed honestly.