CVE-2026-18816 Overview
CVE-2026-18816 is an improper authentication vulnerability [CWE-287] in Baserow versions up to and including 2.3.2. The flaw resides in the verify function within backend/src/baserow/api/two_factor_auth/views.py, part of the 2FA Verify Endpoint. An authenticated attacker can manipulate the verification flow remotely to bypass the second authentication factor. The attack has high complexity and exploitation is considered difficult. Baserow addressed the issue in version 2.3.3 following coordinated disclosure with the vendor.
Critical Impact
Successful exploitation weakens the two-factor authentication (2FA) protection layer for Baserow accounts, reducing the effectiveness of a control designed to defeat credential theft.
Affected Products
- Baserow versions up to and including 2.3.2
- Baserow backend/src/baserow/api/two_factor_auth/views.py — 2FA Verify Endpoint component
- Fixed in Baserow 2.3.3
Discovery Timeline
- 2026-08-04 - CVE-2026-18816 published to NVD
- 2026-08-05 - Last updated in NVD database
Technical Details for CVE-2026-18816
Vulnerability Analysis
The vulnerability affects the verify function in the Baserow 2FA Verify Endpoint. The endpoint is responsible for validating a user-supplied one-time code during the second stage of authentication. Improper handling within this function allows an attacker with low privileges (an existing session or partially authenticated context) to influence the verification result. The attacker must operate over the network but requires no user interaction on the victim side. Because the attack complexity is high, exploitation depends on precise conditions rather than trivial payload delivery.
Root Cause
The root cause is improper authentication logic in verify within backend/src/baserow/api/two_factor_auth/views.py. The function does not sufficiently enforce the security invariants expected of a 2FA verification step. As a result, the endpoint can be manipulated in a way that undermines the guarantee that a valid second factor was presented. See GitHub Baserow Issue #5743 for tracking details.
Attack Vector
The attack vector is network-based against the Baserow backend API. An attacker interacts with the 2FA verification endpoint using crafted requests during the two-factor challenge. Low privileges are required, meaning the actor typically possesses valid primary credentials or a pre-2FA session token. No end-user interaction is needed. Because no verified proof-of-concept has been published, refer to the VulDB entry for CVE-2026-18816 and the Baserow 2.3.3 release notes for further technical context.
Detection Methods for CVE-2026-18816
Indicators of Compromise
- Repeated or anomalous requests to the Baserow 2FA verify endpoint (/api/user/2fa/verify/ or equivalent route served by two_factor_auth/views.py).
- Successful authentication events for accounts with 2FA enabled that lack a corresponding valid TOTP challenge in application logs.
- Session establishment from unexpected geographies or IP ranges shortly after 2FA verification calls.
Detection Strategies
- Correlate authentication logs to identify sessions that reached authenticated state without a preceding, matching 2FA challenge issuance.
- Alert on high request rates or abnormal response patterns against the 2FA verify route, which may indicate probing of the flawed logic.
- Track Baserow application version across deployments and flag any instance running 2.3.2 or earlier.
Monitoring Recommendations
- Enable verbose logging on the Baserow backend authentication routes and forward logs to a centralized SIEM.
- Monitor for privilege changes or API token creation events immediately following 2FA verification calls.
- Baseline normal 2FA verification volume per user and alert on deviations that could indicate abuse of the verification logic.
How to Mitigate CVE-2026-18816
Immediate Actions Required
- Upgrade all Baserow instances to version 2.3.3 or later, which contains the vendor fix.
- Inventory internal and external Baserow deployments and confirm the running version through the admin interface or container image tag.
- Invalidate active sessions and rotate API tokens for accounts that may have authenticated during the vulnerable window.
Patch Information
The vendor released the fix in Baserow 2.3.3. Upgrade instructions and change notes are available in the Baserow 2.3.3 release. Source code for the corrected verify function is available in the Baserow GitHub repository.
Workarounds
- If immediate upgrade is not possible, restrict network exposure of the Baserow backend to trusted networks or place it behind an authenticating reverse proxy.
- Temporarily disable remote access for accounts with elevated privileges until the upgrade is applied.
- Enforce strong primary credentials and monitor sign-in activity closely, since the 2FA layer cannot be fully trusted on affected versions.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
