What is CVE-2021-21609?

CVE-2021-21609 is a medium-severity vulnerability in Jenkins, classified under Incorrect Authorization. CVSS score: 5.3/10. Published 2021-01-13.

How severe is CVE-2021-21609?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Auth bypass in Jenkins

CVE-2021-21609

Jenkins 2.274 and earlier, LTS 2.263.1 and earlier does not correctly match requested URLs to the list of always accessible paths, allowing attackers without Overall/Read permission to access some URLs as if they did have Overall/Read permission.

Vulnerability class: Broken Access Control

Published 2021-01-13 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.

EPSS exploit prediction

EPSS: 0.013 (69.4th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 69th percentile — 69.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.013 · newest: 0.013 · change: 0.000

Affected products

Jenkins
Jenkins Project — versions unspecified

Weakness classification (CWE)

CWE-863 — Incorrect Authorization

References

www.jenkins.io/security/advisory/2021-01-13/ (Vendor Advisory)

Frequently asked questions

What is CVE-2021-21609?: CVE-2021-21609 is a medium-severity vulnerability in Jenkins, classified under Incorrect Authorization. CVSS score: 5.3/10. Published 2021-01-13.
How severe is CVE-2021-21609?: Medium severity. CVSS v3 base score is 5.3 out of 10.