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CVE-2026-48896 is a vulnerability in the multi-factor authentication (MFA) flow of Joomla CMS. The root cause is insufficient state checks in the authentication logic, which allows a remote, unauthenticated attacker to completely bypass the second verification factor.
In a correctly implemented MFA process, after a user supplies a valid password, the system enters a pending state that expects a second credential (e.g., a one‑time token). The vulnerability arises because Joomla fails to properly validate the sequential state of each authentication step. An attacker can send a specially crafted sequence of login requests that skips the second‑factor verification step entirely. By calling a specific endpoint that should be accessible only after full authentication, the attacker can move directly from password validation to a fully authenticated session, without ever presenting the required 2FA token.
This flaw is classified under CWE-287 (Improper Authentication) and CWE-613 (Insufficient Session State Management). It exists because the session object does not persist a flag indicating that MFA has been successfully completed. After the initial password check, the application does not enforce a state machine that forces the login process to pass through the MFA verification. Consequently, an attacker can replay a legitimate session identifier that is already in the “password‑validated” state and directly invoke the final login completion routine.
The attack vector is remote and requires no privileges. The CVSS v4 base score is 8.2 (High), with the vector string CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N. The impact on integrity is high, as an attacker can gain full access to a user account without ever possessing the physical second factor (e.g., a hardware token or mobile device). As of the analysis date, no public proof-of-concept exploit exists, but the EPSS probability of exploitation within the next 30 days is estimated at 0.01%.
DailyCVE Form:
Platform: Joomla CMS
Version: 4.0.0‑6.1.0
Vulnerability: 2FA bypass
Severity: High (8.2)
Date: 2026‑05‑26
Prediction: 2026‑05‑26
What Undercode Say:
Simulate insufficient session state using cURL Step 1: Authenticate with valid password, capture session cookie curl -X POST https://target.com/index.php?option=com_users&task=user.login \ -d "username=admin&password=validpass&return=aW5kZXgucGhw" \ -c session.txt Step 2: Attempt to bypass 2FA by directly accessing the post‑login endpoint curl -X GET https://target.com/index.php?option=com_users&view=profile \ -b session.txt Step 3: Confirm elevated access (administrator panel) without entering 2FA token curl -X GET https://target.com/administrator/index.php \ -b session.txt
How Exploit:
An attacker must first obtain or guess valid credentials (username/password). After a successful password login, the session cookie lacks a verified `mfa_status` flag. By directly navigating to any authenticated endpoint (e.g., /administrator/), the Joomla core does not re‑check whether the second factor was completed, thereby granting full access. The vulnerable code exists in `libraries/src/Application/CMSApplication.php` where the `authenticate()` method fails to enforce a mandatory state transition for MFA.
Protection:
1. Upgrade immediately to Joomla 5.4.6 or 6.1.1.
- If upgrading is not possible, manually enforce MFA state in a custom system plugin:
if ($this->user->get('mfa_verified') !== true) { $this->setHeader('HTTP/1.1 403 Forbidden'); exit; } - Restrict access to the `/administrator` endpoint via IP whitelist or WAF rule.
- Monitor authentication logs for repeated password‑only logins without subsequent MFA entries.
Impact:
Successful exploitation allows an unauthenticated, remote attacker to bypass the second factor of authentication for any user account. The attacker gains the same privileges as the compromised account (e.g., administrator, super user), leading to full site takeover, data exfiltration, deployment of malicious extensions, and potential lateral movement to the underlying server. Since the MFA mechanism is completely skipped, standard defense‑in‑depth measures are nullified, and the only remaining security is the strength of the primary password.
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Sources:
Reported By: nvd.nist.gov
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