PhanSpeed runs a root daemon that accepts commands over a local Unix socket, so security is taken seriously.

Please do not open a public issue for security problems. Instead use GitHub's private reporting:

1. Go to the repo's Security tab → Report a vulnerability.
2. Describe the issue, affected version, and a reproduction if possible.

You'll get a response as soon as reasonably possible.

The relevant attacker is an unprivileged local process abusing the root daemon. There is no network attack surface — the daemon binds only an AF_UNIX socket (IPAddressDeny=any, RestrictAddressFamilies=AF_UNIX).

Hardening in place (see the daemon and systemd/phanspeed.service):

• SO_PEERCRED authorization — only root and configured allow_uids may issue commands; the socket is owned by the user, mode 0660.
• All input is clamped/validated on the socket and on config load. emergency_temp is hard-capped (95 °C) so the thermal failsafe can never be disabled; safety invariants are always enforced.
• DoS-resistant — 64 KB read cap, per-command rate limiting.
• Sandboxed unit — exactly one capability (CAP_CHOWN, only to hand the socket + status file to the logged-in user), ProtectSystem=strict, MemoryDenyWriteExecute, SystemCallFilter=@system-service, private tmp/devices/keyring, least-privilege file modes. DevicePolicy=closed with a DeviceAllow for only the NVIDIA nodes (for optional GPU power control via nvidia-smi); no other device access.
• allow_uids fallback is narrow, not "any session" — with none configured (never the shipped default, which is set to the installing user), the daemon falls back to root + the single seat owner, not every logged-in session.
• /etc/phanspeed/config.json is mode 0600, root-owned only.

The daemon has no network access; phanspeed-update is the one component that does, so it gets its own threat model. As of v0.25.0:

• The daily timer runs it with --check only — it checks and logs, it never installs unattended. Installing a new .deb happens interactively, either via the pill's pkexec prompt or an explicit sudo phanspeed update run.
• Install fails closed on integrity: no SHA256SUMS asset, no matching entry for the exact .deb, or a hash mismatch all abort rather than installing anyway. (This is still corruption/tamper-of-transit protection over HTTPS + checksum, not a cryptographic signature — GPG/minisign signing is a planned hardening step.)
• The download is written to an unpredictable mkstemp() file (O_EXCL, mode 0600) instead of a predictable name in world-writable /tmp, and the unit has PrivateTmp=yes — closing a symlink/TOCTOU write-through a local user could otherwise set up.
• The response body is capped (128 MiB) so a compromised or MITM'd endpoint can't exhaust memory on the root process.

Adversarial tests live in tests/attack_socket.py and assert the failsafe invariants hold under fuzzing. Please keep them passing in any security-relevant PR.