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The ValidateArgumentType RPC endpoint, located in service/internal/api/api.go, lacks any authentication or authorization checks, unlike every other data-returning API endpoint in OliveTin. Other endpoints properly call `auth.UserFromApiCall` and `checkDashboardAccess` to verify the caller’s identity and permissions before returning data. The ValidateArgumentType handler, however, bypasses these security controls entirely.
This flaw manifests only when the security-conscious configuration `AuthRequireGuestsToLogin: true` is enabled. In this mode, guest users are locked out of the dashboard and all other authenticated endpoints. The ValidateArgumentType endpoint remains unintentionally exposed, providing an unauthenticated oracle for enumerating internal server configuration.
The oracle works by returning different HTTP status codes based on the validity of the supplied `bindingId` and `argumentName` parameters. A request with a valid binding ID and a valid argument name returns a `200 OK` response with a JSON body containing {"valid": true/false, "description": "..."}. A request with a valid binding ID but an invalid argument name returns a `CodeNotFound` error. A request with an entirely invalid binding ID also returns a `CodeNotFound` error. While the error messages for the latter two cases are identical, an attacker can distinguish between them by observing whether the response is a `200 OK` or an error.
The oracle is made significantly more dangerous by the predictability of binding IDs. Binding IDs are generated as the SHA256 hash of the action’s human-readable (e.g., “Ping”, “Restart Service”, “Deploy”). An attacker can precompute hashes for a dictionary of common action s and systematically test them against the endpoint to discover which actions exist on the server. Once a valid binding ID is identified, the attacker can then brute-force argument names by testing likely candidates and observing which ones yield a `200 OK` response.
This information disclosure allows an unauthenticated attacker to map out the server’s entire action set and their argument structures. This reconnaissance can be a stepping stone for more targeted attacks, such as the `ot_` prefix argument injection vulnerability or social engineering campaigns. The vulnerability has been assigned CVE-2026-48709 and is fixed in OliveTin version 3000.13.0.
DailyCVE Form:
Platform: OliveTin
Version: <=3000.0.0
Vulnerability: Missing Authentication
Severity: LOW (CVSS 3.7)
date: 2026-06-15
Prediction: Already patched (3000.13.0)
What Undercode Say:
Analytics of the vulnerability reveals that the core issue is a missing authorization check (CWE-862) in a single API handler. The following commands can be used to verify and exploit the vulnerability:
Step 1: Verify that other endpoints require authentication
curl -s -X POST http://localhost:1337/api/GetDashboard \
-H "Content-Type: application/json" \
-d "{}"
Expected output: CodePermissionDenied - "guests are not allowed to access the dashboard"
Step 2: Enumerate binding IDs by guessing action s
Test if an action d "Ping" exists
BINDING_ID=$(echo -n "Ping" | sha256sum | cut -d" " -f1)
curl -s -X POST http://localhost:1337/api/ValidateArgumentType \
-H "Content-Type: application/json" \
-d "{\"bindingId\":\"$BINDING_ID\",\"argumentName\":\"test\",\"value\":\"x\",\"type\":\"ascii\"}"
If action exists: returns CodeNotFound (argument "test" not found)
If action does not exist: returns CodeNotFound (same message)
Step 3: Enumerate argument names for a known binding
Test if argument "target" exists for the Ping action
curl -s -X POST http://localhost:1337/api/ValidateArgumentType \
-H "Content-Type: application/json" \
-d "{\"bindingId\":\"$BINDING_ID\",\"argumentName\":\"target\",\"value\":\"test\",\"type\":\"ascii\"}"
If argument exists: returns {valid: true/false} (200 OK) -- CONFIRMED
If argument does not exist: returns CodeNotFound error
Exploit:
An attacker can exploit this vulnerability by sending unauthenticated POST requests to the `/api/ValidateArgumentType` endpoint. By systematically varying the `bindingId` and `argumentName` fields, the attacker can determine which actions and arguments are configured on the server. The attack requires no credentials and can be performed remotely. The lack of authentication makes it a low-effort reconnaissance technique.
Protection:
The recommended fix is to add the standard authentication and dashboard access checks to the `ValidateArgumentType` handler, bringing it in line with all other data-returning endpoints. The patched code should include:
func (api oliveTinAPI) ValidateArgumentType(ctx ctx.Context, req connect.Request[apiv1.ValidateArgumentTypeRequest]) (connect.Response[apiv1.ValidateArgumentTypeResponse], error) {
// Add auth check consistent with other endpoints
user := auth.UserFromApiCall(ctx, req, api.cfg)
if err := api.checkDashboardAccess(user); err != nil {
return nil, err
}
// ... rest of the handler
}
Upgrading to OliveTin version 3000.13.0 or later eliminates this vulnerability.
Impact:
- Information Disclosure: Unauthenticated attackers can enumerate all configured actions (by testing binding IDs) and their associated arguments (by testing argument names), revealing the server’s internal configuration.
- Reconnaissance for Further Attacks: The enumerated information provides valuable intelligence for launching more targeted attacks, such as the `ot_` prefix argument injection or social engineering.
- Limited Scope: The vulnerability is only exploitable when `AuthRequireGuestsToLogin: true` is configured. In the default configuration, guests already have full dashboard access and the same information is publicly available.
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Sources:
Reported By: github.com
Extra Source Hub:
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