What is CVE-2026-123840?

CVE-2026-123840 is a medium-severity vulnerability in Jetbrains Intellij Idea, classified under Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS). CVSS score: 4.7/10. Published 2026-11-06.

How severe is CVE-2026-123840?

Medium severity. CVSS v3 base score is 4.7 out of 10.

XSS in Jetbrains Intellij Idea

CVE-2026-123840

In JetBrains IntelliJ IDEA before 2026.3 hTML injection was possible in Remote Development editor tabs

Published 2026-11-06 · last modified 2026-11-06.

CVSS v3 metric

CVSS v3 base score 4.7 (Medium). Vector: CVSS:3.1/AV:N/AC:H/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

Jetbrains Intellij Idea

Weakness classification (CWE)

CWE-80 — Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)

References

www.jetbrains.com/privacy-security/issues-fixed/

Frequently asked questions

What is CVE-2026-123840?: CVE-2026-123840 is a medium-severity vulnerability in Jetbrains Intellij Idea, classified under Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS). CVSS score: 4.7/10. Published 2026-11-06.
How severe is CVE-2026-123840?: Medium severity. CVSS v3 base score is 4.7 out of 10.