Unauthenticated CAPTCHA bypass via reusable answers
Published May 16, 2021 · Updated Jul 9, 2026
Improper authentication in Liferay Portal 7.3.4 and 7.3.5 and Liferay DXP 7.3 before fix pack 1 allows remote attackers to reuse CAPTCHA answers. The SimpleCaptcha implementation retains a valid answer after successful use instead of invalidating it, so the same answer remains accepted for later requests. No authentication or user interaction is required; reuse bypasses the intended gate and permits repeated execution of actions protected only by that CAPTCHA.
Summary
What happened
Improper authentication in Liferay Portal 7.3.4 and 7.3.5 and Liferay DXP 7.3 before fix pack 1 allows remote attackers to reuse CAPTCHA answers. The SimpleCaptcha implementation retains a valid answer after successful use instead of invalidating it, so the same answer remains accepted for later requests. No authentication or user interaction is required; reuse bypasses the intended gate and permits repeated execution of actions protected only by that CAPTCHA.
The record
- CVE
- CVE-2021-29047
- Published
- May 16, 2021
- Updated
- Jul 9, 2026
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-287
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 16, 2021CVE publishedPublication date reported by the CVE source.
- Jul 9, 2026Record updatedLatest update available in the CVE record.
Exploitability
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What is affected?
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Attacks
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Technologies
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