CVE-2026-62685: File Browser directory traversal and isolation bypass via username normalization collision

CVE-2026-62685 · Severity: high · CVSS 8.1 · Published 2026-07-15

File Browser, a web-based file management utility, contains a flaw in how it assigns storage folders to new users. When self-registration is enabled, the system simplifies usernames to create folder names (for example, turning 'user/one' and 'user-one' into the same folder). This allows a malicious actor to register a specific username that grants them full access to another user's private files, leading to data theft or unauthorized file modification.

Technologies: File Browser, github.com/filebrowser/filebrowser (Go), github.com/filebrowser/filebrowser/v2 (Go). Vendors: File Browser, Go.

Quick answers

Is CVE-2026-62685 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-62685 being exploited in the wild.
How severe is CVE-2026-62685?
High severity, with a CVSS score of 8.1, published 15 July 2026.
Which products and versions are affected?
File Browser < 2.63.17, <= 2.63.16; github.com/filebrowser/filebrowser (Go) SEMVER:introduced=0; github.com/filebrowser/filebrowser/v2 (Go) <= 2.63.16, SEMVER:introduced=0,fixed=2.63.17.
Is there a fix for CVE-2026-62685?
Yes. github.com/filebrowser/filebrowser/v2 (Go): upgrade to 2.63.17 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-62685 attacked?
It is attacked over the network, in a network appliance.
Am I affected by CVE-2026-62685?
Check whether you run File Browser, github.com/filebrowser/filebrowser (Go) or github.com/filebrowser/filebrowser/v2 (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • github.com/filebrowser/filebrowser/v2 (Go): upgrade to 2.63.17 or later
    go get github.com/filebrowser/filebrowser/v2@v2.63.17

Technical details

The vulnerability exists in the `cleanUsername()` function within `settings/dir.go`, which performs a many-to-one normalization of usernames by stripping '..' and replacing non-alphanumeric characters with dashes. When `Signup` and `CreateUserDir` are enabled, File Browser fails to verify if the resulting normalized 'scope' (home directory) is already assigned to an existing user. An attacker can register a username that normalizes to a victim's existing scope (e.g., 'alice/' colliding with 'alice'), gaining full read/write access to the victim's files. The issue is addressed in version 2.63.17.

Affected products

  • File Browser filebrowser/filebrowser/v2 <= 2.63.16

Identifiers

  • CVE-2026-62685
  • GHSA-7rc3-g7h6-22m7
  • GO-2026-6024

Timeline

  • 2026-07-04: advisory: Initial GitHub Advisory published
  • 2026-07-20: disclosed: Full advisory disclosure and timeline update

References

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