PSA-2026-00061: Proxmox Backup Server: Missing validation of chunk sizes during pull sync
This Proxmox advisory covers a security issue in Proxmox Backup Server.
Key facts
- Fixed in
- proxmox-backup-server 4.2.8-1
- Advisory id
- PSA-2026-00061
- Source published
- Listed by VulniPulse
Compiled by VulniPulse from the linked sources. How records are collected and checked.
Affected products & platforms
Description
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. Packages: proxmox-backup-server.
Text from the source record.
Fix and mitigation
Upgrade to a fixed release named by Proxmox:
- proxmox-backup-server 4.2.8-1
Vendor guidance
- Update to the fixed package versions: proxmox-backup-server >= 4.2.8-1.
End-of-life dates for Proxmox Backup Server
More Proxmox advisories
PSA-2026-00099Nov 10, 2026Proxmox: Incomplete validation of UPID when handling "stop task" API requestsPSA-2026-00087Nov 10, 2026Proxmox Backup Server: Missing privilege check in sync-job modificationPSA-2026-00086Nov 10, 2026Proxmox Backup Server: Missing protections against bogus snapshot creationPSA-2026-00062Oct 7, 2026Proxmox Backup Server: Missing privilege checksPSA-2026-00060Oct 7, 2026Proxmox Backup Server: Missing privilege checks when removing namespace from prune jobPSA-2026-00059Oct 7, 2026Proxmox Backup Server: pxar/container restore target rootfs escape
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