Cross-user file access via colliding username normalization
Published Jul 15, 2026 · Updated Jul 15, 2026
Improper access control in File Browser before 2.63.17 allows remote attackers to read and write another user's files through self-registration. MakeUserDir passes each signup name through cleanUsername(), whose many-to-one replacements can derive an existing scope without a uniqueness check. Exploitation requires Signup and CreateUserDir to be enabled; a second registrant then shares the victim's home directory and can read, overwrite, rename, or delete its files.
Summary
What happened
Improper access control in File Browser before 2.63.17 allows remote attackers to read and write another user's files through self-registration. MakeUserDir passes each signup name through cleanUsername(), whose many-to-one replacements can derive an existing scope without a uniqueness check. Exploitation requires Signup and CreateUserDir to be enabled; a second registrant then shares the victim's home directory and can read, overwrite, rename, or delete its files.
The record
- CVE
- CVE-2026-62685
- Published
- Jul 15, 2026
- Updated
- Jul 15, 2026
- Vendor
- File Browser Contributors
- Product
- File Browser
- Classifications
- CWE-706, CWE-647, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 15, 2026CVE publishedPublication date reported by the CVE source.
- Jul 15, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 2.63.17
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- GHSA-7rc3-g7h6-22m7 proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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