CVE-2026-77026: Convert Forms Auth Bypass Vulnerability

CVE-2026-77026 Overview

CVE-2026-77026 affects the Convert Forms extension for Joomla, developed by tassos.gr. The vulnerability exists in versions prior to 5.2.5 and stems from a client-controlled validation bypass in the front-end Submissions view. The extension fails to enforce server-side access control on this view. An unauthenticated remote visitor can list a form's submissions without providing credentials. The flaw maps to [CWE-602] Client-Side Enforcement of Server-Side Security.

Critical Impact
Unauthenticated attackers can enumerate form submission data, exposing information submitted by legitimate users to the affected forms.

Affected Products

Convert Forms extension for Joomla by tassos.gr
All versions prior to 5.2.5
Joomla sites deploying the front-end Submissions view

Discovery Timeline

2026-08-20 - CVE-2026-77026 published to NVD
2026-08-20 - Last updated in NVD database

Technical Details for CVE-2026-77026

Vulnerability Analysis

The Convert Forms extension exposes a front-end Submissions view intended for authorized users to review data submitted through Joomla forms. The vulnerability arises because access control checks execute on the client side rather than being enforced by the server. An attacker who bypasses or ignores the client-side check can still reach the underlying endpoint and receive submission data in the response.

Because the flaw is a design-level access control failure, no memory corruption or code execution is required. The attacker simply issues a crafted HTTP request to the front-end Submissions endpoint. The server returns submission records without validating the requester's identity or role. This confidentiality impact is limited to whatever data users have entered into forms, which may include names, email addresses, and free-text fields.

Root Cause

The root cause is client-controlled enforcement of a security decision, categorized under [CWE-602]. The Submissions view relies on front-end logic to gate access instead of performing authorization checks on the server before returning data. Removing or ignoring the client-side control exposes the underlying data path.

Attack Vector

The attack vector is network-based and requires no authentication or user interaction. An attacker enumerates Joomla installations running Convert Forms below version 5.2.5, then queries the front-end Submissions endpoint directly. Because the endpoint responds without an authorization check, the attacker receives listings of prior form submissions.

No verified exploit code is publicly available for CVE-2026-77026. Refer to the Tassos Convert Forms product page for vendor information.

Detection Methods for CVE-2026-77026

Indicators of Compromise

Unauthenticated HTTP requests to Convert Forms front-end Submissions endpoints originating from unknown IP ranges
Anomalous volumes of GET requests to Joomla index.php with Convert Forms view or component parameters referencing submissions
Outbound data patterns showing form submission content returned to unauthenticated sessions

Detection Strategies

Review Joomla and web server access logs for requests targeting Convert Forms submission views without a valid authenticated session cookie
Deploy web application firewall (WAF) rules that block or alert on unauthenticated access to submission listing endpoints
Baseline normal administrator access patterns to the Submissions view and alert on deviations from anonymous or external sources

Monitoring Recommendations

Enable verbose logging on the Joomla site and forward logs to a centralized SIEM or data lake for retention and query
Correlate access log spikes with the version of Convert Forms installed on each Joomla host
Monitor for scanning behavior enumerating Joomla extensions and versions across the perimeter

How to Mitigate CVE-2026-77026

Immediate Actions Required

Upgrade the Convert Forms extension to version 5.2.5 or later on all Joomla installations
Inventory Joomla sites to identify any host still running a vulnerable Convert Forms build
Review recent access logs for evidence of unauthenticated access to the Submissions view

Patch Information

Upgrade Convert Forms to version 5.2.5 or later, which introduces server-side access control on the Submissions view. Refer to the Tassos Convert Forms product page for release information and download links.

Workarounds

Restrict access to Convert Forms front-end Submissions URLs at the web server or WAF layer until the patch is applied
Temporarily disable the front-end Submissions view within Convert Forms configuration if it is not required
Rotate or invalidate any sensitive data collected through affected forms if unauthenticated access is confirmed in logs

bash

# Example nginx rule to block unauthenticated access to Convert Forms submissions view
location ~* "option=com_convertforms.*view=submissions" {
    return 403;
}