CVE-2026-62843: File Browser path traversal in archive builder via backslash filenames

Executive brief

File Browser is a web-based file management utility. A vulnerability in its archive creation feature allows users with upload permissions to plant malicious files that, when downloaded and extracted by another user, can write files to arbitrary locations on the victim's computer. This could lead to the overwrite of sensitive system files or the execution of malicious code on the victim's machine.

Technical details

A path traversal vulnerability (Zip-Slip) exists in File Browser's archive builder. The root cause is an improper fix for a previous vulnerability where backslashes in filenames are unconditionally replaced with forward slashes. On POSIX systems (Linux/macOS), backslashes are legal filename characters; replacing them with slashes manufactures a traversal sequence (e.g., '..\\..\\' becomes '../../'). An attacker with 'Create' permissions can upload a file with a crafted name containing backslashes. When a victim downloads the containing folder as a ZIP or Tar archive, the resulting archive contains entries that escape the extraction directory. This affects versions 2.63.6 through 2.63.16 and is fixed in 2.63.17.

Affected products

• filebrowser filebrowser >= 2.63.6, <= 2.63.16

Timeline

• 2026-07-04: disclosed
• 2026-07-20: advisory
• 2026-07-20: patched: Fixed in version 2.63.17

References

• https://api.github.com/users/je-lv
• https://github.com/je-lv
• https://api.github.com/users/je-lv/gists%7B/gist_id%7D
• https://api.github.com/users/je-lv/repos
• https://avatars.githubusercontent.com/u/40743233?v=4
• https://api.github.com/users/je-lv/events%7B/privacy%7D