Missing validation of chunk sizes during pull sync

Details

An attacker with control over a pull source (or its raw index contents) could trick the pull target into storing an index file with an invalid reference to a valid chunk. Subsequent verification of that index will treat the chunk as corrupt, breaking availability of other valid snapshots referencing it.

This issue was reported privately by Project Loupe.

Fixed in

• proxmox-backup-server >= 4.2.8-1