GHSA-XFX2-PRG5-JQ3G: Gin-Gonic Middleware Bypass: Authorization Failure in INSATutorat

Source: Dev.to

Overview

Vulnerability ID: GHSA-XFX2-PRG5-JQ3G
CVSS Score: 8.8
Published: 2026-03-01

A critical authorization bypass vulnerability exists in the INSATutorat application due to improper middleware implementation within the Gin‑Gonic web framework. The AdminHandler middleware, designed to protect administrative routes, fails to terminate the request lifecycle upon detecting unauthorized access. Consequently, authenticated non‑administrative users can bypass security controls and execute privileged actions on endpoints under /api/admin/*, leading to potential data loss and unauthorized system management.

TL;DR

The INSATutorat application contains a critical flaw in its administrative middleware. While the code correctly identifies unauthorized users, it fails to halt the request processing chain (missing c.Abort()). This allows any authenticated user to successfully invoke administrative API endpoints regardless of their privileges.

Exploit Status

POC

Technical Details

• CWE ID: CWE-285
• CVSS v3.1: 8.8
• Attack Vector: Network
• Privileges Required: Low
• Impact: High (Confidentiality & Integrity)
• Platform: Go (Gin‑Gonic)

Affected Systems

• INSATutorat (Go Application) – Fixed in commit 15ae47425aed337181f7a6c54a9d199c93b041eb

Code Analysis

Commit: 15ae474

Fix admin middleware authorization bypass by adding c.Abort():

func AdminHandler() gin.HandlerFunc {
    return func(c *gin.Context) {
        userInterface, exists := c.Get("user")
        if !exists {
            _ = c.Error(apierrors.Unauthorized)
            c.Abort()
            return
        }

        user := userInterface.(*models.User)
        if !user.IsAdmin {
            _ = c.Error(apierrors.Forbidden)
            c.Abort()
            return
        }

        // Continue processing for authorized admin users
        c.Next()
    }
}

Mitigation Strategies

• Immediate patching of the middleware logic.
• Audit all Gin middleware for missing Abort() calls.
• Implement integration tests that assert correct HTTP status codes for unauthorized requests.

Remediation Steps

1. Locate middlewares/admin.go in the source code.
2. Insert c.Abort() immediately before each return in error‑handling branches.
3. Rebuild and redeploy the application.
4. Verify the fix by attempting to access /api/admin/ endpoints with a non‑admin account.

References

• GitHub Advisory GHSA‑XFX2‑PRG5‑JQ3G
• INSATutorat Repository