How severe is CVE-2021-21684?

CVE-2021-21684 has a CVSS score of 6.1/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2021-21684?

CVE-2021-21684 affects the following packages: org.jenkins-ci.plugins:git (Maven). Ecosystems affected: Maven.

How do I fix CVE-2021-21684?

Update org.jenkins-ci.plugins:git to 4.8.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-21684 is resolved across your whole dependency graph.

How do I detect CVE-2021-21684 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.jenkins-ci.plugins:git, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2021-21684 if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is CVE-2021-21684 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-21684 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2021-21684?

CVE-2021-21684 has an EPSS (Exploit Prediction Scoring System) score of 1.2%, placing it in the 69th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2021-21684?

CVE-2021-21684 is classified as CWE-116 (CWE-116). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2021-21684 published, and has it been updated?

CVE-2021-21684 was published on October 6, 2021 and was last updated on October 24, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕

☕ Maven

Not in CISA KEV

MEDIUM severity

CVE-2021-21684 — git

MEDIUMFix: jenkinsci/git-plugin@5474cc9

CVE-2021-21684 is a medium-severity (CVSS 6.1) CWE-116 vulnerability in org.jenkins-ci.plugins:git. A fix is available for org.jenkins-ci.plugins:git — see the affected versions and patch details below.

Stored XSS vulnerability in Jenkins Git Plugin

Also known asGHSA-gghc-g8cj-4vfv

Published

Oct 6, 2021

Updated

Oct 24, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 7, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs69th percentile — riskier than 69% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

☕org.jenkins-ci.plugins:git

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

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.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.jenkins-ci.plugins:git`	all versions	4.8.3`org.jenkins-ci.plugins:git:4.8.3`

Affected Products

1 product · 1 configurations

Application

gitjenkins

≤ 4.8.2

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.jenkins-ci.plugins:git, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.jenkins-ci.plugins:git to 4.8.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-21684 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

This vulnerability is only exploitable in Jenkins 2.314 and earlier, LTS 2.303.1 and earlier [1] [1] https://www.jenkins.io/doc/upgrade-guide/2.303/#SECURITY-2452

Product	Fixed in	Advisory
Red Hat OpenShift Container Platform 4.10	`jenkins-2-plugins-0:4.10.1643404185-1.el8`	RHSA-2022:0055

Frequently Asked Questions

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 u

O3 Security · Impact-Aware SCA

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CVSS Score

6.1/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Raw vector

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

CWE Classification

CWE-116CWE-116

Weaponization

No Nuclei template, Metasploit module or public proof-of-concept found.

Timeline

Disclosed

Oct 6, 2021

Last updated

Oct 24, 2026

Identifiers

CVE-2021-21684

GHSA-gghc-g8cj-4vfv

References

Advisoryopenwall.com Advisoryjenkins.io · 2021 10 06 Advisorynvd.nist.gov · CVE 2021 21684 Webgithub.com · 5474cc942bfba60927be629ff47fb41c38c66741 Packagegithub.com · git plugin

Related vulnerabilities

This CVE is medium severity; 7 of 8 other CVEs affecting git are rated as high or higher (top: high).

CVE-2022-38663CVE-2022-36884CVE-2022-36882CVE-2022-36883CVE-2020-2136CVE-2022-30947CVE-2022-30949CVE-2017-1000092

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedOct 24, 2026