What is CVE-2026-120421?

CVE-2026-120421 is a medium-severity vulnerability in Eclipse Foundation Mojarra, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-11-04.

How severe is CVE-2026-120421?

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

XSS in Eclipse Foundation Mojarra

CVE-2026-120421

In Eclipse Mojarra versions 2.2.0 through 4.0.28, 4.1.0 through 4.1.19, and 5.0.0-M1 through 5.0.0-M11, when URL client window mode is enabled (`jakarta.faces.CLIENT_WINDOW_MODE=url`), the client window id from the `jfwid` or `jakarta.faces.ClientWindow` request parameter is appended to generated URLs without URL-encoding. `h:button` renders such a URL into a JavaScript string literal, which allows reflected cross-site scripting. With `com.sun.faces.enableCspNonce=true`, the injected script runs on page load inside the nonce script element, bypassing the Content Security Policy.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2026-11-04 · last modified 2026-11-04.

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

Eclipse Foundation Mojarra

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

Frequently asked questions

What is CVE-2026-120421?: CVE-2026-120421 is a medium-severity vulnerability in Eclipse Foundation Mojarra, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-11-04.
How severe is CVE-2026-120421?: Medium severity. CVSS v3 base score is 6.1 out of 10.