What is CVE-2026-100522?

CVE-2026-100522 is a medium-severity vulnerability in Cotonti, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-09-26.

How severe is CVE-2026-100522?

Medium severity. CVSS v3 base score is 6.1 out of 10.

XSS in Cotonti

CVE-2026-100522

Cotonti through 1.0.0 contains a reflected cross-site scripting vulnerability in message.php where the lng parameter is not properly escaped before output in the confirmation dialog. Unauthenticated attackers can craft malicious links with script payloads in the lng parameter to execute arbitrary JavaScript in victim browser sessions.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2026-09-26 · last modified 2026-09-26.

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

Cotonti

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

github.com/Cotonti/Cotonti (product)
github.com/Cotonti/Cotonti/blob/1.0.0/message.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-reflected-xss-via-message-ph… (third-party-advisory)

Frequently asked questions

What is CVE-2026-100522?: CVE-2026-100522 is a medium-severity vulnerability in Cotonti, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-09-26.
How severe is CVE-2026-100522?: Medium severity. CVSS v3 base score is 6.1 out of 10.