CVE-2026-42223

Ein Angreifer kann mehrere Schwachstellen in nginx-ui ausnutzen, um beliebigen Code mit Root-Rechten auszuführen, sich Administratorrechte zu verschaffen und die vollständige Kontrolle über das System zu erlangen oder vertrauliche Informationen offenzulegen.

### Summary The `GetSettings` API handler (`api/settings/settings.go:24-65`) serializes all settings structs to JSON and returns them to authenticated users. Many sensitive fields are tagged with `protected:"true"` - however, this tag is only enforced during writes (via `ProtectedFill` in `SaveSettings`) and is completely ignored during reads. This exposes 40+ protected fields including `JwtSecret` (enabling auth token forgery), `NodeSecret` (enabling cluster node impersonation), OIDC `ClientSecret` (enabling OAuth account takeover), and the IP whitelist configuration. ### Details #### Vulnerable Code **`api/settings/settings.go:49-64` - GetSettings serializes all fields** ```go c.JSON(http.StatusOK, gin.H{ "app": cSettings.AppSettings, "server": cSettings.ServerSettings, "database": settings.DatabaseSettings, "auth": settings.AuthSettings, "casdoor": settings.CasdoorSettings, "oidc": settings.OIDCSettings, "cert": settings.CertSettings, "http": settings.HTTPSettings, "logrotate": settings.LogrotateSettings, "nginx": settings.NginxSettings, "node": settings.NodeSettings, "openai": settings.OpenAISettings, "terminal": settings.TerminalSettings, "webauthn": settings.WebAuthnSettings, }) ``` Go's `json.Marshal` serializes all exported fields with `json:` tags. The `protected:"true"` struct tag is a custom tag - it has no effect on JSON serialization. #### Protection is Write-Only **`api/settings/settings.go:126-135` - ProtectedFill only used during saves** ```go cSettings.ProtectedFill(cSettings.AppSettings, &json.App) cSettings.ProtectedFill(cSettings.ServerSettings, &json.Server) cSettings.ProtectedFill(settings.AuthSettings, &json.Auth) // ... etc ``` `ProtectedFill` prevents overwriting protected fields during `SaveSettings`, but `GetSettings` has no corresponding filter. The protection is asymmetric - secrets can be read but not overwritten. #### Exposed Protected Fields **`settings/node.go`:** - `Secret` (protected) - used for cluster node authentication - `SkipInstallation` (protected), `Demo` (protected) **`settings/oidc.go` (all protected):** - `ClientId`, `ClientSecret`, `Endpoint`, `RedirectUri`, `Scopes`, `Identifier` **`settings/casdoor.go` (all protected):** - `Endpoint`, `ExternalUrl`, `ClientId`, `ClientSecret`, `CertificatePath`, `Organization`, `Application`, `RedirectUri` **`settings/auth.go`:** - `IPWhiteList` (protected) - exposes security configuration #### Attack Scenario 1. Low-privilege authenticated user calls `GET /api/settings` 2. Response includes `NodeSecret` - attacker can impersonate cluster nodes 3. Response includes OIDC `ClientSecret` - attacker can perform OAuth flows as the application 4. Response includes `IPWhiteList` - attacker learns network security configuration 5. If `JwtSecret` is in app settings (via cosy framework), attacker can forge authentication tokens for any user ### PoC **1. `GetSettings` serializes all fields** without filtering `protected:"true"` tags. From `api/settings/settings.go:49-64`: ```go c.JSON(http.StatusOK, gin.H{ "app": cSettings.AppSettings, "server": cSettings.ServerSettings, "database": settings.DatabaseSettings, "auth": settings.AuthSettings, "casdoor": settings.CasdoorSettings, "oidc": settings.OIDCSettings, "cert": settings.CertSettings, "http": settings.HTTPSettings, "logrotate": settings.LogrotateSettings, "nginx": settings.NginxSettings, "node": settings.NodeSettings, "openai": settings.OpenAISettings, "terminal": settings.TerminalSettings, "webauthn": settings.WebAuthnSettings, }) ``` Go's `json.Marshal` serializes all exported fields. The custom `protected:"true"` tag has no effect on serialization. **2. Protected secrets are defined** across `settings/*.go`. High-impact examples: ```go // settings/server_v1.go:19 JwtSecret string `json:"jwt_secret" protected:"true"` // settings/node.go:5 Secret string `json:"secret" protected:"true"` // settings/oidc.go ClientSecret string `json:"client_secret" protected:"true"` // settings/auth.go IPWhiteList []string `json:"ip_white_list" protected:"true"` ``` **3. `ProtectedFill` is write-only.** It appears 10 times in `SaveSettings` (lines 126-135) but 0 times in `GetSettings`: ```go // api/settings/settings.go:126-135 - Only used during writes cSettings.ProtectedFill(cSettings.AppSettings, &json.App) cSettings.ProtectedFill(cSettings.ServerSettings, &json.Server) cSettings.ProtectedFill(settings.AuthSettings, &json.Auth) // ... 7 more calls ``` **4. Exploit request.** Any authenticated user can retrieve all secrets: ```http GET /api/settings HTTP/1.1 Authorization: Bearer <any-valid-jwt> ``` Response includes (among 45 protected fields): ```json { "app": {"jwt_secret": "<the-actual-jwt-signing-key>", ...}, "node": {"secret": "<node-authentication-secret>", ...}, "oidc": {"client_secret": "<oidc-client-secret>", ...}, "casdoor": {"client_secret": "<casdoor-client-secret>", ...}, "auth": {"ip_white_list": ["10.0.0.1", ...], ...}, "nginx": {"reload_cmd": "nginx -s reload", "restart_cmd": "...", ...} } ``` ### Impact - **Authentication bypass via JwtSecret**: An attacker who obtains the `JwtSecret` can forge valid JWT tokens for any user, including admin accounts. This provides permanent, independent access that survives password changes and session revocations. - **Cluster compromise via NodeSecret**: The `NodeSecret` is used for inter-node authentication in nginx-ui clusters. An attacker can impersonate any cluster node, push malicious configurations to all nodes, and intercept cluster synchronization traffic. - **Third-party OAuth takeover**: Leaked OIDC `ClientSecret` and Casdoor `ClientSecret` allow the attacker to perform OAuth flows as the nginx-ui application, potentially gaining access to user accounts on the identity provider. - **Security configuration disclosure**: The `IPWhiteList`, `ReloadCmd`, `RestartCmd`, `ConfigDir`, `SbinPath`, and other protected fields reveal the security posture and infrastructure layout, enabling more targeted attacks. - **Low barrier to exploitation**: Any authenticated user (not just admins) can access `GET /api/settings`. In multi-user deployments, a low-privilege operator can escalate to full admin access. ### Remediation Filter out `protected:"true"` fields before serialization.

Nginx-UI Settings API Exposes Protected Secrets in github.com/0xJacky/nginx-ui. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. (If this is causing false-positive reports from vulnerability scanners, please suggest an edit to the report.) The additional affected modules and versions are: github.com/0xJacky/nginx-ui before v2.3.8.