CVE-2026-54089
Starting with 2.0.0-rc.1, when FileBrowser is configured with proxy authentication (auth.method=proxy), any unauthenticated attacker who can reach the server directly can impersonate any user - including admin - by sending a single forged HTTP header.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.61%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
File Browser is a file managing interface for uploading, deleting, previewing, renaming, and editing files within a specified directory. Starting with 2.0.0-rc.1, when FileBrowser is configured with proxy authentication (auth.method=proxy), any unauthenticated attacker who can reach the server directly can impersonate any user - including admin - by sending a single forged HTTP header. No credentials are required. Additionally, specifying a non-existent username causes the server to automatically create a new user account, providing an account creation primitive with no authorization. This is an already known issue that has been documented in the documentation for several years, but has not been documented as a vulnerability before.
- CVSS 3.1
- 9.1 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
- EPSS
- 0.61% probability · 47th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-287, CWE-290
- Source
- security-advisories@github.com
References
- https://github.com/filebrowser/filebrowser/blob/main/auth/proxy.go
- https://github.com/filebrowser/filebrowser/blob/main/http/auth.go#L121-L137
- https://github.com/filebrowser/filebrowser/security/advisories/GHSA-xqp3-jq6g-x3qm
- https://github.com/filebrowser/filebrowser/security/advisories/GHSA-xqp3-jq6g-x3qm
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.