Authenticated restricted-file access via unnormalized URL paths
Published Feb 9, 2026 · Updated Feb 9, 2026
Authorization bypass in File Browser before 2.57.1 allows remote authenticated users to read or alter disallowed files via crafted URLs. The router preserves repeated slashes, while rules/rules.go applies strings.HasPrefix to the unnormalized path before the filesystem collapses those separators. A configured Disallow rule and a valid account are required; the bypass grants reads and, with general write rights, file renaming, deletion, or modification.
Summary
What happened
Authorization bypass in File Browser before 2.57.1 allows remote authenticated users to read or alter disallowed files via crafted URLs. The router preserves repeated slashes, while rules/rules.go applies strings.HasPrefix to the unnormalized path before the filesystem collapses those separators. A configured Disallow rule and a valid account are required; the bypass grants reads and, with general write rights, file renaming, deletion, or modification.
The record
- CVE
- CVE-2026-25890
- Published
- Feb 9, 2026
- Updated
- Feb 9, 2026
- Vendor
- File Browser Contributors
- Product
- File Browser
- Classifications
- CWE-863, CWE-706, T1190
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Feb 9, 2026CVE publishedPublication date reported by the CVE source.
- Feb 9, 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=< 2.57.2
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
- GitHub advisory minimal Python 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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