What is CVE-2021-21621?

CVE-2021-21621 is a medium-severity vulnerability in Jenkins Support Core, classified under Information Disclosure. CVSS score: 5.3/10. Published 2021-02-24.

How severe is CVE-2021-21621?

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

Information disclosure in Jenkins Support Core

CVE-2021-21621

Jenkins Support Core Plugin 2.72 and earlier provides the serialized user authentication as part of the "About user (basic authentication details only)" information, which can include the session ID of the user creating the support bundle in some configurations.

Vulnerability class: Information Disclosure

Published 2021-02-24 · 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: 0.012 (67.1th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 67th percentile — 67.1% 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 Support Core
Jenkins Project Support Core Plugin — versions unspecified, 2.70.1, 2.68.1

Weakness classification (CWE)

CWE-200 — Information Disclosure

References

www.jenkins.io/security/advisory/2021-02-24/ (Vendor Advisory)

Frequently asked questions

What is CVE-2021-21621?: CVE-2021-21621 is a medium-severity vulnerability in Jenkins Support Core, classified under Information Disclosure. CVSS score: 5.3/10. Published 2021-02-24.
How severe is CVE-2021-21621?: Medium severity. CVSS v3 base score is 5.3 out of 10.