Only the latest release on the main branch receives security fixes.

Mellivora OS is a bare-metal educational operating system that runs directly on hardware (or QEMU). It includes a full TCP/IP networking stack (RTL8139 NIC driver, ARP, IPv4, ICMP, UDP, TCP, DHCP, DNS) and has no user authentication. Security concerns include:

• Buffer overflows in kernel or shell code that could corrupt memory or escalate privilege (Ring 3 → Ring 0)
• Network stack vulnerabilities — malformed packets, integer overflows in protocol parsers, or boundary errors in the BSD-style socket API (8 simultaneous sockets)
• Filesystem integrity issues in HBFS that could cause data loss or corruption
• Build chain safety — ensuring the Makefile, Python scripts, and tooling don't introduce vulnerabilities
• Syscall boundary validation — ensuring user-mode programs cannot pass invalid pointers or sizes to kernel syscalls

If you discover a security issue, please report it responsibly:

1. Do NOT open a public GitHub issue for security vulnerabilities.
2. Use GitHub's private vulnerability reporting: Report a vulnerability
3. Include:
   • Description of the vulnerability
   • Steps to reproduce (assembly snippet, shell command, or disk image)
   • Impact assessment (crash, memory corruption, privilege escalation, data loss)
   • Suggested fix if you have one

• Acknowledgment: Within 72 hours
• Assessment: Within 1 week
• Fix release: As soon as practical, typically within 2 weeks for confirmed issues

The project actively hardens its codebase. Recent examples:

• v7.3: Fixed black-screen hang in VBE games caused by missing VBE_GAME_PRESENT call; removed redundant KEY_UP/KEY_DOWN/KEY_LEFT/KEY_RIGHT %ifndef guards in vbe_game.inc that caused inconsistent redefinition errors
• v7.0: Shell prompt placement fix — vga_cursor_x is checked before emitting prompt to prevent output corruption at column boundaries
• v6.5: audio.inc and highscore.inc libraries validated for bounds on score path construction; hs_update only writes when candidate beats stored value
• v6.1: VBE UI library (vbe_ui.inc) introduced with input-length guards on modal and text-input widgets
• Earlier: Fixed build_cwd_path buffer overflow, added bounded copy_word_n, ATA retry wrappers with soft reset, HBFS error propagation with carry flag, nested batch execution guard, superblock free_blocks consistency tracking