CVE-2021-21610

Name: CVE-2021-21610
Creator: NVD / NIST
Published: 2021-01-13T16:15:14.007+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.1/10EPSS 1.19%

Last modified Jun 17, 2026

CVE-2021-21610 is a medium-severity vulnerability rated 6.1/10 on the CVSS scale. Jenkins 2.274 and earlier, LTS 2.263.1 and earlier does not implement any restrictions for the URL rendering a formatted preview of markup passed as a query parameter, resulting in a reflected cross-site scripting (XSS) vulnerability if the configured markup formatter does not prohibit unsafe elements (JavaScript) in markup.. EPSS estimates a 1.19% chance of exploitation in the next 30 days.

Description

Jenkins 2.274 and earlier, LTS 2.263.1 and earlier does not implement any restrictions for the URL rendering a formatted preview of markup passed as a query parameter, resulting in a reflected cross-site scripting (XSS) vulnerability if the configured markup formatter does not prohibit unsafe elements (JavaScript) in markup.

Metrics

CVSS 3.1

6.1/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS Probability

1.19%

63.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-79

Affected Software

Vendor	Product	Versions
Jenkins	Jenkins	<= 2.263.1
Jenkins	Jenkins	<= 2.274

References

https://www.jenkins.io/security/advisory/2021-01-13/#SECURITY-2153Vendor Advisory
https://www.jenkins.io/security/advisory/2021-01-13/#SECURITY-2153Vendor Advisory

Timeline

Published: Jan 13, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-21610?

How severe is CVE-2021-21610?

CVE-2021-21610 has a CVSS score of 6.1/10 (MEDIUM severity). The EPSS model estimates a 1.19% probability of exploitation in the next 30 days.

How do I fix CVE-2021-21610?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-21610?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST