What is CVE-2021-27733?

CVE-2021-27733 is a medium-severity vulnerability in Jetbrains Youtrack, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2021-05-11.

How severe is CVE-2021-27733?

Medium severity. CVSS v3 base score is 5.4 out of 10.

XSS in Jetbrains Youtrack

CVE-2021-27733

In JetBrains YouTrack before 2020.6.6441, stored XSS was possible via an issue attachment.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2021-05-11 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.006 (45.4th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 45th percentile — 45.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: 0.000

Affected products

Jetbrains Youtrack

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

blog.jetbrains.com (Vendor Advisory)
blog.jetbrains.com/blog/2021/05/07/jetbrains-security-bulletin-q1-2021/ (Vendor Advisory)

Frequently asked questions

What is CVE-2021-27733?: CVE-2021-27733 is a medium-severity vulnerability in Jetbrains Youtrack, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2021-05-11.
How severe is CVE-2021-27733?: Medium severity. CVSS v3 base score is 5.4 out of 10.