SB2026040745 - Time-of-check Time-of-use (TOCTOU) Race Condition in Parse Server
Published: April 7, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 security vulnerability.
1) Time-of-check Time-of-use (TOCTOU) Race Condition (CVE-ID: CVE-2026-33624)
The vulnerability allows a remote user to bypass single-use restrictions on MFA recovery codes.
The vulnerability exists due to a time-of-check time-of-use race condition in the login handler when processing concurrent login requests that use an MFA recovery code. A remote privileged user can send concurrent login requests with a valid password and recovery code to bypass single-use restrictions on MFA recovery codes.
Exploitation requires possession of the user's password, a valid recovery code, and the ability to issue concurrent requests within milliseconds.
Remediation
Install update from vendor's website.