Only the latest release receives security fixes. Runner Manager updates itself from Releases, so updating is the fix.

Do not open a public issue for a security problem. Report it privately instead:

1. Open the Security tab of this repository.
2. Click Report a vulnerability, and describe the problem, the affected version and how to reproduce it.

You get a reply within a week. Please give a reasonable time to release a fix before you disclose the problem.

Runner Manager runs with administrator rights and listens on the network, so these areas matter most:

• Fleet connection (TCP 47821, UDP 47822): requests between PCs are encrypted and authenticated with AES-256-GCM, bound to the target PC and a timestamp, and checked against replays.
• Pairing (TCP 47823, UDP 47824, only while a PC is being added): ECDH P-256, confirmed with a 6-digit code. The new PC commits to its key before it sees the other one, so a device in between cannot make the codes match.
• PCs managed one way: such a PC gets a pairing code of its own instead of the fleet's. The fleet's PCs use that code to reach it, but they never accept it themselves, so the managed PC cannot see or control them, even with a modified Runner Manager. Removing it, or changing the fleet code, gives it a new code that a PC with the old one doesn't know.
• Stored secrets: the pairing code, and the codes of PCs managed one way, are encrypted with Windows DPAPI for the current user.
• Runner configuration: runner names, labels and URLs are checked before they reach config.cmd.
• Updates: releases are verified with their SHA-256 checksum before they replace the installed copy, and an older version is never installed over a newer one.
• AI assistants (off by default): tool calls go to the fleet agent on the same PC. The assistant and the agent prove to each other with Windows DPAPI that they run as the same Windows user, and changes (including stopping a stuck job's processes) ask for approval in a Runner Manager window. Connect by URL listens on 127.0.0.1 only and needs a bearer token.

Out of scope: problems that need administrator access to the PC already, and the security of GitHub Actions runners themselves.