CVE-2026-59240: IDOR Authentication Bypass Vulnerability

CVE-2026-59240 Overview

CVE-2026-59240 is an Insecure Direct Object Reference (IDOR) vulnerability in Prospero Flow CRM. The flaw exists in the DeleteNotificationController::delete() method exposed at GET /notification/delete/{id}. Any authenticated user can delete notifications belonging to any other user, irrespective of company or role boundaries. The controller retrieves the target record using Notification::findOrFail($id) and deletes it without validating user_id or company_id ownership. Because notification identifiers are sequential integers, an attacker can iterate through IDs to systematically wipe notifications across the entire tenant base. The vulnerability is tracked under CWE-639: Authorization Bypass Through User-Controlled Key.

Critical Impact
Authenticated attackers can enumerate sequential notification IDs and delete alerts belonging to any user, suppressing visibility of ticket alerts, task assignments, and system events across all tenants.

Affected Products

Prospero Flow CRM versions prior to v5.5.3
Deployments exposing the /notification/delete/{id} endpoint to authenticated users
Multi-tenant instances where notification IDs are globally sequential

Discovery Timeline

2026-07-27 - CVE-2026-59240 published to NVD
2026-07-28 - Last updated in NVD database

Technical Details for CVE-2026-59240

Vulnerability Analysis

The vulnerability resides in the DeleteNotificationController class within Prospero Flow CRM's notification subsystem. The delete() action accepts an integer $id parameter directly from the URL and passes it to Eloquent's Notification::findOrFail($id). This lookup queries the notification by primary key alone, without applying any ownership constraint. Once retrieved, the record is deleted through $notification->delete() and the user is redirected back to the previous page.

The sibling controller SetNotificationReadAjaxController correctly scopes lookups by Auth::id(), which confirms that ownership enforcement was expected but omitted for the delete path. Because notification records use auto-incremented identifiers, an attacker can script GET requests against a monotonic ID range to erase notifications belonging to arbitrary users.

Root Cause

The root cause is missing authorization on a direct object reference. The controller trusts a client-supplied identifier without verifying that the authenticated principal owns the referenced record. This is a textbook [CWE-639] pattern where authentication is enforced but per-object authorization is not.

Attack Vector

Exploitation requires only an authenticated session on the target instance. The attacker issues sequential GET requests to /notification/delete/{id}, incrementing {id} to enumerate and delete every notification in the database. No CSRF token bypass is needed for a same-origin authenticated session, and no elevated role is required.

php

// Patch: app/Http/Controllers/Notification/DeleteNotificationController.php
 use App\Http\Controllers\MainController;
 use App\Models\Notification;
+use Illuminate\Support\Facades\Auth;
 
 class DeleteNotificationController extends MainController
 {
     public function delete(int $id)
     {
-        $notification = Notification::findOrFail($id);
+        $notification = Notification::where('id', $id)
+            ->where('user_id', Auth::id())
+            ->firstOrFail();
         $notification->delete();
 
         return redirect()->back();

Source: GitHub commit eaee2ae. The patch adds an Auth::id() ownership filter so that non-owners receive a 404 from firstOrFail() instead of a successful deletion.

Detection Methods for CVE-2026-59240

Indicators of Compromise

Sequential GET /notification/delete/{id} requests from a single authenticated session within a short time window
HTTP 302 redirect responses to /notification/delete/{id} for IDs not belonging to the requesting user
Sudden drops in notification counts across multiple user_id values in the notifications table
User reports of missing ticket, task, or system event alerts without corresponding server errors

Detection Strategies

Deploy web server or WAF rules that count /notification/delete/ requests per session and alert on burst enumeration patterns
Correlate application logs with the notifications table to flag deletions where the acting Auth::id() does not match the deleted record's user_id
Add an application-level audit trigger that records every notification deletion with actor, target owner, and timestamp

Monitoring Recommendations

Ingest Prospero Flow CRM access logs into a centralized log platform and alert on high-cardinality ID enumeration against /notification/delete/
Baseline expected notification deletion volume per user and alert on outliers exceeding two standard deviations
Monitor database write patterns for high-rate DELETE FROM notifications statements originating from web sessions

How to Mitigate CVE-2026-59240

Immediate Actions Required

Upgrade Prospero Flow CRM to v5.5.3 or later, which contains the ownership check
Audit the notifications table for anomalous deletion activity prior to patching and restore from backup if bulk deletions are observed
Rotate session tokens for accounts that may have abused the endpoint and review authentication logs for suspicious activity

Patch Information

The fix is committed as eaee2ae and shipped in release v5.5.3. The patch replaces the unscoped Notification::findOrFail($id) call with a query that filters by both id and the authenticated user_id, forcing a 404 when a caller references a notification they do not own. Additional analysis is available in the Secur0 CVE-2026-59240 write-up.

Workarounds

Restrict access to /notification/delete/{id} at the reverse proxy or WAF until the upgrade is applied
Add a middleware that resolves the target Notification and rejects requests where notification.user_id !== Auth::id()
Rate-limit the notification deletion endpoint per session to slow enumeration-based abuse

bash

# Example nginx rule to rate-limit and log the vulnerable endpoint
limit_req_zone $binary_remote_addr zone=notif_del:10m rate=5r/m;

location ~ ^/notification/delete/[0-9]+$ {
    limit_req zone=notif_del burst=3 nodelay;
    access_log /var/log/nginx/notif_delete.log combined;
    proxy_pass http://prospero_backend;
}