Open Redirect in Cotonti
CVE-2026-100523
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.
Vulnerability class: Open Redirect
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/Cotonti/Cotonti (product)
- github.com/Cotonti/Cotonti/blob/1.0.0/message.php (technical-description)
- github.com/Cotonti/Cotonti/blob/1.0.0/system/common.php (technical-description)
- github.com/Cotonti/Cotonti/issues/1907 (issue-tracking)
- github.com/Cotonti/Cotonti/pull/1908 (issue-tracking, patch)
- www.vulncheck.com/advisories/cotonti-through-1.0.0-open-redirect-via-message-ph… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-100523?
- CVE-2026-100523 is a medium-severity vulnerability in Cotonti, classified under URL Redirection to Untrusted Site (Open Redirect). CVSS score: 6.1/10. Published 2026-09-26.
- How severe is CVE-2026-100523?
- Medium severity. CVSS v3 base score is 6.1 out of 10.