CVE-2026-34206 Captcha Protect: Reflected XSS in challenge page via unsanitized destination rendered with text/template
Attackers can inject arbitrary scripts into the anti-bot challenge page via unsanitized destination parameters, potentially compromising user sessions.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-34206?
CVE-2026-34206 is a medium-severity cross-site scripting vulnerability in libops captcha-protect, published on 31 Mar 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
Captcha Protect is a Traefik middleware to add an anti-bot challenge to individual IPs in a subnet when traffic spikes are detected from that subnet. Prior to version 1.12.2, a reflected cross-site scripting (XSS) vulnerability exists in github.com/libops/captcha-protect. The challenge page accepted a client-supplied destination value and rendered it into HTML using Go's text/template. Because text/template does not perform contextual HTML escaping, an attacker could supply a crafted destination value that breaks out of the hidden input attribute and injects arbitrary script into the challenge page. This issue has been patched in version 1.12.2.
Weakness: CWE-79
Which versions are affected by CVE-2026-34206?
It affects 1 product.
Products include Libops Captcha Protect.
How do I fix CVE-2026-34206?
No fix has been published for CVE-2026-34206 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-34206 being exploited?
There is no known exploitation of CVE-2026-34206 in the wild and no public exploit code.
Sources
Also known as GHSA-ph62-4j5g-2q4r.