CVE-2021-21684

Description

Jenkins Git Plugin 4.8.2 and earlier does not escape the Git SHA-1 checksum parameters provided to commit notifications when displaying them in a build cause. This results in a stored cross-site scripting (XSS) vulnerability exploitable by attackers able to submit crafted commit notifications to the `/git/notifyCommit` endpoint. Jenkins Git Plugin 4.8.3 rejects Git SHA-1 checksum parameters that do not match the expected format. Existing values are sanitized when displayed on the UI. This vulnerability is only exploitable in Jenkins 2.314 and earlier, LTS 2.303.1 and earlier. See the [LTS upgrade guide](https://www.jenkins.io/doc/upgrade-guide/2.303/#SECURITY-2452).

How to fix CVE-2021-21684

To remediate CVE-2021-21684, upgrade the affected package to a fixed version below.

• —upgrade to 4.8.3 or later

Is CVE-2021-21684 being exploited?

Low — EPSS is 0.6%, meaning exploitation activity has not been observed at scale.

Affected packages (1)

• from 0, < 4.8.3

CVSS scores

References (5)

• ADVISORYnvd.nist.gov/vuln/detail/CVE-2021-21684
• PATCHgithub.com/jenkinsci/git-plugin
• WEBgithub.com/jenkinsci/git-plugin/commit/5474cc942bfba60927be629ff47fb41c38c66741
• WEBwww.jenkins.io/security/advisory/2021-10-06/#SECURITY-2499