Executive brief
mayswind ezBookkeeping is a personal bookkeeping application that supports two-factor authentication via TOTP codes. Before version 2.0.0, the application failed to invalidate TOTP codes after single use, allowing attackers who obtained user credentials and a captured authentication code to reuse that code repeatedly for about 90 seconds. This could enable account takeover without the legitimate user being aware their credentials were compromised.
Technical details
The vulnerability is a TOTP replay flaw in the two-factor authentication implementation. An attacker with valid credentials can capture a TOTP code and replay it during the acceptance window (approximately 90 seconds) for multiple authentication attempts, bypassing the intended security mechanism of single-use codes. The fix, released in version 2.0.0, implements proper passcode invalidation after a single use.
Affected products
- mayswind ezBookkeeping before 2.0.0
Timeline
- 2026-09-20: disclosed
- 2026-09-16: patched: v2.0.0 released with TOTP passcode invalidation fix