PBP restores backups on Proxmox VE nodes and installs a helper there that runs as root through one sudo rule, so a vulnerability in it can matter a great deal. Please report one privately.

Use GitHub's private vulnerability reporting: the repository's Security tab → Report a vulnerability. Do not open a public issue or pull request for a vulnerability.

Include what you can of:

• the affected version (pbp version) and where it runs (PBP host, Proxmox node, Docker or .deb);
• what an attacker needs first (a stolen SSH key, the API token, a guest under their control, access to the PBP host);
• what they gain, and how to reproduce it;
• any fix you have in mind.

You will get an acknowledgement within 7 days. Once a fix is released, the report is credited in the CHANGELOG unless you ask otherwise.

Only the newest release gets security fixes. PBP's daemon and node helper must share major.minor, so upgrade both sides as Upgrading describes.

• the daemon (pbp daemon, pbp run, pbp check, pbp health, pbp setup);
• the node helper (pbp node), its SSH forced command, its sudo rule, and pbp node setup / uninstall;
• the packages, the release files and their signatures, and the install line pbp setup prints.

Security model explains what PBP is allowed to touch on the node (its VMID range and pbp-tagged guests only), what the API token and SSH key can and cannot do, and the guests PBP deliberately does not proof. A way around any of those limits is in scope.

Every release's SHA256SUMS is signed with PBP's SSH signing key, fingerprint SHA256:HzEvo7r8x719x/XzBa5JDQFsFdsw79kNXIdaUt2a7a8. See Verifying a release.