CVE-2026-72836

Description

FileBrowser before 2.63.19 does not account for case-insensitive filesystems when checking home directory ownership during self-registration. When Signup and CreateUserDir are enabled and FileBrowser's root is on a case-insensitive filesystem (confirmed on Windows/NTFS), two self-registered usernames that differ only in letter case (e.g., CaseVictim and casevictim) are stored as distinct accounts but resolve to the same physical home directory, because the scope-ownership check compares the persisted scope as an exact case-sensitive string. A second registrant can therefore read, overwrite, and delete another account's files through authenticated HTTP endpoints, without needing an existing account or victim interaction.

CVSS Metrics

• v4.0•CRITICAL•Score: 9.2CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
• v4.0•CRITICAL•Score: 9.2CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
• v3.1•HIGH•Score: 8.1CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Techniques & Countermeasures

• CWE-178•Improper Handling of Case Sensitivity

  The product does not properly account for differences in case sensitivity when accessing or determining the properties of a resource, leading to inconsistent results.

Affected Systems

• filebrowser•filebrowser

  < 2.63.19

References (3)

• https://github.com/filebrowser/filebrowser/security/advisories/GHSA-576v-w77m-gr84
• https://github.com/filebrowser/filebrowser/commit/fe7efb2e6afe66774cd86a5b0a03033bd514d0c0
• https://www.vulncheck.com/advisories/filebrowser-before-case-sensitivity-authentication-bypass