What’s Vulnerable › Vulnerabilities

CVE-2026-100523: Cotonti through 1.0.0 Open Redirect via message.php redirect parameter

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-26 · updated 2026-10-05
• Weakness: CWE-601

Description

Cotonti through 1.0.0 contains an open redirect vulnerability in message.php that base64-decodes the redirect parameter without domain validation. Unauthenticated attackers can craft malicious links with encoded external URLs to redirect users to arbitrary sites via meta refresh tags for phishing attacks.

Affected products

• Cotonti: through 1.0.0

References

• https://github.com/Cotonti/Cotonti
• https://github.com/Cotonti/Cotonti/blob/1.0.0/message.php
• https://github.com/Cotonti/Cotonti/blob/1.0.0/system/common.php
• https://github.com/Cotonti/Cotonti/issues/1907
• https://github.com/Cotonti/Cotonti/pull/1908
• https://www.vulncheck.com/advisories/cotonti-through-1.0.0-open-redirect-via-message-php-redirect-parameter

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