CVE-2026-62232: Grav CMS 2FA Bypass Vulnerability

CVE-2026-62232 Overview

CVE-2026-62232 is a two-factor authentication bypass vulnerability in the Grav flat-file content management system (CMS). The flaw exists in the login plugin's regenerate2FASecret task, which validates only user existence rather than authorization during the pending Time-based One-Time Password (TOTP) challenge window. An attacker who already knows a victim's password can invoke this task without a Cross-Site Request Forgery (CSRF) nonce to overwrite the stored 2FA secret with an attacker-controlled value. The attacker then computes a valid TOTP code from the new secret and completes login, effectively downgrading 2FA protection to password-only. The issue is tracked under CWE-862: Missing Authorization and is fixed in Grav 2.0.4.

Critical Impact
Attackers with knowledge of a victim's password can bypass 2FA and take over Grav administrator accounts by overwriting the TOTP secret during authentication.

Affected Products

Grav CMS versions prior to 2.0.4
Grav login plugin (bundled component containing the vulnerable regenerate2FASecret task)
Grav administrative interfaces protected by TOTP-based two-factor authentication

Discovery Timeline

2026-07-17 - CVE-2026-62232 published to the National Vulnerability Database (NVD)
2026-07-17 - Last updated in NVD database

Technical Details for CVE-2026-62232

Vulnerability Analysis

Grav's login plugin implements 2FA as a two-step flow. A user first submits a valid username and password, then completes a TOTP challenge to finalize the session. During this pending challenge window, the plugin exposes a regenerate2FASecret task intended for legitimate users who need to reset a lost authenticator.

The vulnerable handler confirms only that the target account exists. It does not validate that the request originates from an authorized session, and it does not require a CSRF nonce. This turns a self-service reset feature into an authentication bypass primitive, as documented in the GitHub Security Advisory GHSA-7mgc-c7pq-3rr3.

Root Cause

The root cause is missing authorization [CWE-862] on a sensitive state-changing operation. The regenerate2FASecret task should require an authenticated, fully authorized session and a valid CSRF token. Instead, it accepts requests during the intermediate authentication state, where the caller has supplied credentials but has not yet proven possession of the second factor.

Attack Vector

Exploitation proceeds in four steps against a network-reachable Grav instance:

The attacker obtains the victim's password through phishing, credential stuffing, or reuse.
The attacker submits the password to begin login, reaching the pending TOTP challenge state.
The attacker invokes the regenerate2FASecret task without a CSRF nonce, causing Grav to overwrite the victim's stored TOTP secret with a value the attacker controls.
The attacker generates a valid TOTP code from the new secret and completes authentication, gaining full account access.

Because the request bypasses CSRF protection, no additional user interaction is required. Refer to the VulnCheck advisory for further exploitation detail.

Detection Methods for CVE-2026-62232

Indicators of Compromise

HTTP POST requests to Grav login endpoints containing the task=regenerate2FASecret parameter without an accompanying CSRF nonce field.
Modifications to Grav user account YAML files (typically under user/accounts/) where the twofa_secret field changes without a corresponding administrator-initiated reset.
Successful admin logins immediately preceded by a regenerate2FASecret request for the same account.

Detection Strategies

Inspect Grav web server access logs for requests targeting the login plugin with the regenerate2FASecret task parameter and correlate them with subsequent successful logins.
Monitor file integrity on the user/accounts/ directory to flag unexpected changes to twofa_secret values.
Alert on authentication sequences where the TOTP secret is rotated within the same session that later completes login.

Monitoring Recommendations

Forward Grav application and web server logs to a centralized log platform for retention and correlation.
Build alerts on repeated failed logins followed by a regenerate2FASecret invocation against the same account.
Track administrative account activity, including source IP addresses and user agent patterns, to identify anomalous logins after the disclosure date.

How to Mitigate CVE-2026-62232

Immediate Actions Required

Upgrade Grav to version 2.0.4 or later, which restricts regenerate2FASecret to fully authorized sessions and enforces CSRF validation.
Force a password reset for all Grav accounts that use 2FA, and require users to re-enroll their TOTP authenticators.
Review recent admin sessions and revoke any suspicious active sessions or API tokens.

Patch Information

The vulnerability is fixed in Grav 2.0.4. The patch adds authorization checks on the regenerate2FASecret task and requires a valid CSRF nonce before allowing the TOTP secret to be rotated. Details are published in the GitHub Security Advisory GHSA-7mgc-c7pq-3rr3.

Workarounds

Restrict access to the Grav admin interface at the network layer using an IP allowlist or Virtual Private Network (VPN) until the patch can be applied.
Place the Grav application behind a Web Application Firewall (WAF) and block HTTP requests containing task=regenerate2FASecret that lack a valid CSRF nonce parameter.
Disable the login plugin's self-service 2FA reset feature where configuration permits, and handle 2FA resets exclusively through administrator workflows.