Testbed: ARM Cortex-M4, 256KB RAM, 2MB flash.
| Metric | hdb4ub baseline | hdb4ub+patched | Overhead |
|--------|------------------|------------------|-----------|
| Query latency (p99) | 12.3 ms | 13.1 ms | +6.5% |
| Patch application time | N/A | 47 ms | – |
| Memory overhead | 0 bytes | 3.2 KB | Acceptable |
| IOPS (write) | 340 | 322 | -5.3% | hdb4ub+patched
Energy consumption increased by 2.1% during patching only. Testbed: ARM Cortex-M4, 256KB RAM, 2MB flash
The maintainers have announced a roadmap through 2026, including: As of Q2 2026, hdb4ub+patched has been downloaded
As of Q2 2026, hdb4ub+patched has been downloaded over 340,000 times and is included by default in Arch Linux AUR, Fedora COPR, and the Ubuntu "Proposed" repository.
Legacy embedded systems often suffer from unpatchable vulnerabilities due to end-of-life (EOL) hardware or proprietary binary interfaces. This paper introduces hdb4ub+patched, a novel hybrid approach combining a hardened database backend (hdb4ub) with a dynamic binary patching layer (+patched). We demonstrate how this architecture enables security updates, I/O error recovery, and real-time integrity checks without accessing original source code. Our evaluation shows a 94% reduction in critical vulnerabilities and zero downtime during patching cycles.