Vulnerability in github.com/gtsteffaniak/filebrowser/backend (CVE-2026-54685)
Summary
Vulnerability in github.com/gtsteffaniak/filebrowser/backend (CVE-2026-54685). Risk of unauthorized operations or information disclosure. Exploitable via Auth. Mitigation: upgrade to 0.0.0-20260317230626-af08800667b8 or later.
Original description
The description as published by the source.
Summary
The /api/auth/login authentication endpoint does not execute in constant time. When a non-existent username is supplied, the server returns a 401/403 response almost immediately. When a valid username is provided, the server performs a bcrypt password comparison, causing a measurable delay in the response time.
Details
The vulnerability exists in the Auth function of JSONAuth in auth/json.go (lines 45–52). The function performs a database lookup for the user prior to performing any password validation.
user, err := userStore.Get(username)
if err != nil {
return nil, fmt.Errorf("unable to get user from store: %v", err)
}
err = users.CheckPwd(password, user.Password)
if err != nil {
return nil, err
}
If the username is not found, the function returns an error immediately. If the username is found, the function calls CheckPwd, which executes the bcrypt hash comparison. Because bcrypt is intentionally computationally expensive, this introduces a measurable delay in the response time.
As a result, an attacker can distinguish valid usernames from invalid ones by measuring the authentication response times.
In testing, responses for valid usernames consistently required approximately 40–50 ms due to the bcrypt comparison, while invalid usernames returned in approximately 1–4 ms.
PoC
The script below automates this attack by calibrating the network latency using non-existent usernames to establish a baseline and then testi…
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-54685 has been found in github.com/gtsteffaniak/filebrowser/backend.
Attackers can target a specific entry point like Auth over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.3/10.
What to do: upgrade github.com/gtsteffaniak/filebrowser/backend to 0.0.0-20260317230626-af08800667b8 or later.
If unsure, ask your IT team or search "github.com/gtsteffaniak/filebrowser/backend CVE-2026-54685" on the vendor's site.
CVE-2026-54685 (github.com/gtsteffaniak/filebrowser/backend) — CWE-208 / CVSS v3 5.3
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: Auth / JSONAuth / CheckPwd / admin
Patched: 0.0.0-20260317230626-af08800667b8 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-208) exists in github.com/gtsteffaniak/filebrowser/backend. Attackers reach the vulnerable code path via Auth without authentication.
Check the vendor advisory for the affected versions of github.com/gtsteffaniak/filebrowser/backend. Attack surface: Auth / JSONAuth / CheckPwd / admin.
Severity: Medium (CVSS 5.3/10). Risk of unauthorized operations or information disclosure.
Update to 0.0.0-20260317230626-af08800667b8.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'github.com/gtsteffaniak/filebrowser/backend' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'github.com/gtsteffaniak/filebrowser/backend' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
github.com/gtsteffaniak/filebrowser/backendを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade github.com/gtsteffaniak/filebrowser/backend to 0.0.0-20260317230626-af08800667b8ステージング環境で 0.0.0-20260317230626-af08800667b8 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- package github.com
- web github.com
- web github.com
- web github.com
- web github.com