CVE-2026-25890High· 8.1▾ MidnightPoC availableFile Browser has a Path-Based Access Control Bypass via Multiple Leading Slashes in URL
▾ Midnight zone — Critical, or high with PoC / in-the-wild
impact 44.6 · likelihood 0.1 · exploitation 12
A public proof-of-concept already exists for this vulnerability — see Exploit availability below.
Public exploit / PoC code seen in 1 source. Availability, not in-the-wild use.
Exploit-prediction probability, daily snapshots since Sep 12.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via OSV
Last analysed / modified upstream
0.5%
1 GitHub repo (last check)
An authenticated user can bypass the application's "Disallow" file path rules by modifying the request URL. By adding multiple slashes (e.g., //private/) to the path, the authorization check fails to match the rule, while the underlying filesystem resolves the path correctly, granting unauthorized access to restricted files.
The vulnerability allows users to bypass "Disallow" rules defined by administrators.
The issue stems from how the application handles URL path normalization and rule matching:
http/http.go is configured with r.SkipClean(true). This prevents the automatic collapse of multiple slashes (e.g., // becoming /) before the request reaches the handler.rules/rules.go relies on a simple string prefix match: strings.HasPrefix(path, r.Path). If a rule disallows /private, a request for //private fails this check because //private does not strictly start with /private.The following steps demonstrate the vulnerability:
This vulnerability impacts the confidentiality and integrity of data stored in filebrowser.
github.com/filebrowser/filebrowser/v2 < 2.57.1Upgrade to a patched release:
github.com/filebrowser/filebrowser/v2 2.57.1Connected by shared product, vendor, weakness, or advisory.
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