Bug 2540830 (CVE-2026-93353)

Summary: CVE-2026-93353 copyparty: copyparty: Unauthorized file modification via SFTP volume restriction bypass
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in copyparty. The Secure File Transfer Protocol (SFTP) service fails to enforce access restrictions during directory creation, removal, and file attribute modification operations. An authenticated remote attacker can exploit this issue by traversing symbolic links that lead outside their authorized storage directories. This allows the attacker to create, modify, or delete arbitrary files and folders outside of their permitted volume on the host system.
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Bug Depends On: 2540972    
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Description OSIDB Bzimport 2026-09-24 20:42:12 UTC 
copyparty contains a volume restriction bypass vulnerability in its SFTP front end that allows authenticated SFTP users to create, remove, and truncate arbitrary paths outside permitted volume boundaries by exploiting three handlers that bypass the xvol volflag enforcement. The _mkdir, _rmdir, and _chattr handlers construct destination paths using vfs.get(), vn.canonical(), and os.path.join() without invoking the chk_ap access check, enabling attackers to traverse symlinks leaving a volume's top directory and perform unauthorized file creation, deletion, or truncation via SSH_FXP_SETSTAT operations on paths outside any volume the account is authorized to access.