Is CVE-2026-100523 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-100523 being exploited in the wild.

How severe is CVE-2026-100523?

Medium severity, with a CVSS score of 6.1, published 26 September 2026.

Is there a fix for CVE-2026-100523?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-100523 attacked?

It is attacked over the network.

Am I affected by CVE-2026-100523?

Check whether you run Cotonti at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-100523: Cotonti open redirect in message.php

CVE-2026-100523 · Severity: medium · CVSS 6.1 · Published 2026-09-26

Cotonti is a PHP content management framework that processes user requests and redirects. The vulnerability allows unauthenticated attackers to craft malicious links that redirect users to arbitrary external websites through base64-encoded parameters, enabling phishing attacks where users are tricked into visiting fraudulent sites.

Technologies: Cotonti. Vendors: Cotonti.

Quick answers

Is CVE-2026-100523 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-100523 being exploited in the wild.
How severe is CVE-2026-100523?: Medium severity, with a CVSS score of 6.1, published 26 September 2026.
Which products and versions are affected?: Cotonti through 1.0.0.
Is there a fix for CVE-2026-100523?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-100523 attacked?: It is attacked over the network.
Am I affected by CVE-2026-100523?: Check whether you run Cotonti at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

The message.php file decodes base64-encoded redirect parameters without validating that the destination is within the same domain, allowing an open redirect vulnerability. Attackers can construct links with encoded external URLs that bypass basic URL validation checks. No authentication is required to exploit this, making it trivial for an attacker to craft and distribute malicious links.

Affected products

Cotonti Cotonti through 1.0.0

Timeline

2026-09-26: disclosed

References

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