Simple CAPTCHA Alternative with Cloudflare Turnstile <= 1.38.0 - Broken Authorization
Strategic Overview
- Status
- Patched in 1.38.1
- Affected Plugin
- Simple CAPTCHA with Cloudflare Turnstile
- Affected Version
<= 1.38.0- CVSS
- 5.3Medium
- Weakness type
- CWE-285 · Improper Authorization
- CVE
CVE-2026-40799
At a glance
CVE-2026-40799 is a medium-severity Improper Authorization vulnerability in the Simple CAPTCHA with Cloudflare Turnstile WordPress plugin, affecting versions <= 1.38.0. It carries a CVSS score of 5.3 (reachable over the network; low attack complexity). Exploitation requires no authentication. The issue is fixed in version 1.38.1; sites on affected versions should update now. Disclosed May 2026, reported by David Marín.
Vulnerability Overview
The Simple CAPTCHA Alternative with Cloudflare Turnstile plugin for WordPress is vulnerable to broken authorization in all versions up to, and including, 1.38.0. This makes it possible for unauthenticated attackers to use one successful Turnstile submission for multiple checks
Technical Analysis
The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no privileges on the target site, and no interaction from a victim user.
CWE-285: Improper Authorization
Reaching this weakness in Simple CAPTCHA with Cloudflare Turnstile <= 1.38.0 takes a caller who can reach the endpoint. Improper authorization means a permission check exists but does not cover the case being exercised, so a caller who is allowed to do one thing is allowed to do a neighbouring thing as well.
A lower-privileged account performs an action reserved for a higher one, which on a multi-author or membership site means an ordinary user reaching administrative behaviour. For Simple CAPTCHA with Cloudflare Turnstile the fix is 1.38.1: builds <= 1.38.0 are affected, anything from 1.38.1 onward is not.
Remediation
Update to version 1.38.1, or a newer patched version
How does WordSec protect against this?
Because it turns on account access, WordSec's login security is the relevant layer: role-based two-factor, captcha and brute-force limits raise the cost of getting the account this needs. None of that substitutes for the fix: Simple CAPTCHA with Cloudflare Turnstile 1.38.1 closes this, and updating the plugin is the step that ends it.
- Login Security
- Alerts
External References
Related records
Other vulnerabilities in Simple CAPTCHA with Cloudflare Turnstile
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