How severe is CVE-2021-21646?

CVE-2021-21646 has a CVSS score of 8.8/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-21646?

CVE-2021-21646 affects the following packages: org.jenkins-ci.plugins:templating-engine (Maven). Ecosystems affected: Maven.

How do I fix CVE-2021-21646?

Update org.jenkins-ci.plugins:templating-engine to 2.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-21646 is resolved across your whole dependency graph.

How do I detect CVE-2021-21646 in my Maven dependencies?

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

How do I mitigate CVE-2021-21646 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2021-21646 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-21646 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-2021-21646?

CVE-2021-21646 has an EPSS (Exploit Prediction Scoring System) score of 1.7%, placing it in the 78th 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.

When was CVE-2021-21646 published, and has it been updated?

CVE-2021-21646 was published on April 21, 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

HIGH severity

CVE-2021-21646 — templating-engine

HIGHFix: jenkinsci/templating-engine-plugin@aed14be

CVE-2021-21646 is a high-severity (CVSS 8.8) remote code execution vulnerability in org.jenkins-ci.plugins:templating-engine. A fix is available for org.jenkins-ci.plugins:templating-engine — see the affected versions and patch details below.

Remote code execution vulnerability in Jenkins Templating Engine Plugin

Also known asGHSA-p6qc-37hq-wqr6

Published

Apr 21, 2021

Updated

Oct 24, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.7%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs78th percentile — riskier than 78% 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:templating-engine

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 Templating Engine Plugin 2.1 and earlier does not protect its pipeline configurations using Script Security Plugin.

This vulnerability allows attackers with Job/Configure permission to execute arbitrary code in the context of the Jenkins controller JVM.

Jenkins Templating Engine Plugin 2.2 integrates with Script Security Plugin to protect its pipeline configurations.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.jenkins-ci.plugins:templating-engine`	all versions	2.2`org.jenkins-ci.plugins:templating-engine:2.2`

Affected Products

1 product · 1 configurations

Application

templating enginejenkins

≤ 2.1

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:templating-engine, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.jenkins-ci.plugins:templating-engine to 2.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-21646 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

Jenkins Templating Engine Plugin 2.1 and earlier does not protect its pipeline configurations using Script Security Plugin. This vulnerability allows attackers with Job/Configure permission to execute arbitrary code in the context of the Jenkins controller JVM. Jenkins Templating Engine Plugin 2.2 integrates with Script Security Plugin to protect its pipeline configurations.

O3 Security · Impact-Aware SCA

Is CVE-2021-21646 in your dependencies?

Find it across Maven, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

8.8/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Raw vector

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

Weaponization

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

Timeline

Disclosed

Apr 21, 2021

Last updated

Oct 24, 2026

Identifiers

CVE-2021-21646

GHSA-p6qc-37hq-wqr6

References

Advisoryopenwall.com Advisoryjenkins.io · 2021 04 21 Advisorynvd.nist.gov · CVE 2021 21646 Webgithub.com · aed14bed7333329f51330d0a8111e4d94cdee3e6 Packagegithub.com · templating engine plugin

Related vulnerabilities

This CVE is high severity, in line with the other 1 CVE affecting templating-engine.

CVE-2025-31722

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedOct 24, 2026

CVE-2021-21646 — templating-engine

EPSS Exploitation Probability

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

Description

Affected Packages

Affected Products

Detection & mitigation playbook

Detect

Fix

Workarounds

Frequently Asked Questions

Is CVE-2021-21646 in your dependencies?