CVE-2021-21640 — jenkins-core
MEDIUMCVE-2021-21640 is a medium-severity (CVSS 4.3) vulnerability in org.jenkins-ci.main:jenkins-core. A fix is available for org.jenkins-ci.main:jenkins-core — see the affected versions and patch details below.
View name validation bypass in Jenkins
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2021-21640 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,166 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
org.jenkins-ci.main:jenkins-core☕org.jenkins-ci.main:jenkins-coreReal-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 2.286 and earlier, LTS 2.277.1 and earlier does not properly check that a newly created view has an allowed name, allowing attackers with View/Create permission to create views with invalid or already-used names.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.jenkins-ci.main:jenkins-core | all versions | 2.277.2org.jenkins-ci.main:jenkins-core:2.277.2 |
| ☕Maven | org.jenkins-ci.main:jenkins-core | ≥ 2.278&&< 2.287 | 2.287org.jenkins-ci.main:jenkins-core:2.287 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.jenkins-ci.main:jenkins-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.jenkins-ci.main:jenkins-core to 2.277.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-21640 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.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2021-21640 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2021-21640. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
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.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat OpenShift Container Platform 4.7 | jenkins-0:2.277.3.1620393611-1.el8 | RHSA-2021:1551 |
| Red Hat OpenShift Container Platform 4.8 | jenkins-0:2.289.1.1624020353-1.el8 | RHSA-2021:2437 |
Frequently Asked Questions
Is CVE-2021-21640 in your dependencies?
O3 Security finds CVE-2021-21640 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.