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CVE-2026-103028 is a security vulnerability residing in SFTPGo, an open-source, event-driven file transfer solution. Specifically, the flaw exists due to how source-side file pattern filters, such as denied_patterns and allowed_patterns, are evaluated during server-side copy operations. In affected software versions ranging from 2.5.0 up to 2.7.6, when a user executes a file or directory copy operation, the application validates filters against the destination path instead of correctly enforcing them on the source files. Because of this validation oversight, an authenticated user possessing standard copy permissions can take a restricted source file—one that should normally be blocked or hidden by policy—and copy it to an unconstrained, permitted destination path. Once successfully copied to the allowed location, the user can freely read the sensitive file contents or recursively duplicate restricted directory trees. While home directory boundaries, virtual layouts, and standard per-directory permissions remain enforced, this bypass compromises file-level visibility controls and allows unauthorized access to restricted data contents. Remediation requires updating the platform instance to version 2.7.6 or later.
DailyCVE Form:
Platform: SFTPGo
Version: 2.5.0 to 2.7.5
Vulnerability : File Filter Bypass
Severity: Moderate
date: Sep 19, 2026
Prediction: Oct 13, 2026
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The vulnerability stems from improper input validation logic where security controls check destination path names instead of performing checks on source parameters during copy workflows. This allows lower-privileged users with standard file copy rights to circumvent naming restrictions and export restricted file contents into accessible directories.
Exploit: (Educational Purposes!)
Example demonstration of invoking copy operation on a restricted file pattern sftpgo-cli cp /restricted-folder/secret.txt /allowed-folder/renamed_secret.txt cat /allowed-folder/renamed_secret.txt
Protection: from this CVE
To protect systems against CVE-2026-103028, administrators must immediately upgrade the SFTPGo package installation to version 2.7.6 where source-side validation checks are properly enforced. Until an upgrade can be applied, restrict copy permissions for untrusted roles and avoid relying solely on name-based pattern filters to secure highly sensitive data objects.
Impact
Authenticated users can bypass filter policies to read sensitive file contents that were otherwise hidden or restricted by pattern rules, though overall account boundaries and virtual folder structures remain secure.
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Sources:
Reported By: github.com
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