What is CVE-2021-21606?

CVE-2021-21606 is a medium-severity vulnerability in Jenkins, classified under Improper Input Validation. CVSS score: 4.3/10. Published 2021-01-13.

How severe is CVE-2021-21606?

Medium severity. CVSS v3 base score is 4.3 out of 10.

Improper input validation in Jenkins

CVE-2021-21606

Jenkins 2.274 and earlier, LTS 2.263.1 and earlier improperly validates the format of a provided fingerprint ID when checking for its existence allowing an attacker to check for the existence of XML files with a short path.

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

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

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N.

EPSS exploit prediction

EPSS: 0.012 (67.4th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 67th percentile — 67.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.012 · newest: 0.012 · change: 0.000

Affected products

Jenkins
Jenkins Project — versions 2.242, unspecified

Weakness classification (CWE)

CWE-20 — Improper Input Validation

References

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

Frequently asked questions

What is CVE-2021-21606?: CVE-2021-21606 is a medium-severity vulnerability in Jenkins, classified under Improper Input Validation. CVSS score: 4.3/10. Published 2021-01-13.
How severe is CVE-2021-21606?: Medium severity. CVSS v3 base score is 4.3 out of 10.