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MEDIUM severity

CVE-2021-21607 — jenkins-core

MEDIUMFix: jenkinsci/jenkins@a890d68

CVE-2021-21607 is a medium-severity (CVSS 6.5) CWE-770 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.

Excessive memory allocation in graph URLs leads to denial of service in Jenkins

Also known asBIT-jenkins-2021-21607GHSA-cxqw-vjcr-gp5g
Published
Jan 13, 2021
Updated
Jul 9, 2026
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed
Exploitation data as of Sep 21, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.4%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs72th percentile — riskier than 72% of all scored CVEsHighest risk

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-2021-21607 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 378,156 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

2 pkgs affected
☕org.jenkins-ci.main:jenkins-core☕org.jenkins-ci.main:jenkins-core

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 renders several different graphs for features like agent and label usage statistics, memory usage, or various plugin-provided statistics.

Jenkins 2.274 and earlier, LTS 2.263.1 and earlier does not limit the graph size provided as query parameters.

This allows attackers to request or to have legitimate Jenkins users request crafted URLs that rapidly use all available memory in Jenkins, potentially leading to out of memory errors.

Jenkins 2.275, LTS 2.263.2 limits the maximum size of graphs to an area of 10 million pixels. If a larger size is requested, the default size for the graph will be rendered instead.

This threshold can be configured by setting the Java system property hudson.util.Graph.maxArea to a different number on startup.

Affected Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
☕Mavenorg.jenkins-ci.main:jenkins-coreall versions2.263.2org.jenkins-ci.main:jenkins-core:2.263.2
☕Mavenorg.jenkins-ci.main:jenkins-core≥ 2.264&&< 2.2752.275org.jenkins-ci.main:jenkins-core:2.275

Detection & mitigation playbook

Open-source dependency

  1. Detect

    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.

  2. Fix

    Update org.jenkins-ci.main:jenkins-core to 2.263.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-21607 is resolved across your whole dependency graph.

  3. 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.

  4. How O3 protects you

    O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2021-21607 can be triaged on real exposure rather than presence alone.

Tailored to CVE-2021-21607. 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.

Red HatModerate
ProductFixed inAdvisory
Red Hat OpenShift Container Platform 3.11jenkins-0:2.263.3.1612433584-1.el7RHSA-2021:0637
Red Hat OpenShift Container Platform 4.5conmon-2:2.0.21-1.rhaos4.5.el7RHSA-2021:0429
Red Hat OpenShift Container Platform 4.6jenkins-0:2.263.3.1612434510-1.el8RHSA-2021:0423
Red Hat OpenShift Container Platform 4.8atomic-openshift-service-idler-0:4.8.0-202106281541.p0.git.39cfc66.assembly.stream.el8RHSA-2021:2437

Frequently Asked Questions

Jenkins renders several different graphs for features like agent and label usage statistics, memory usage, or various plugin-provided statistics. Jenkins 2.274 and earlier, LTS 2.263.1 and earlier does not limit the graph size provided as query parameters. This allows attackers to request or to have legitimate Jenkins users request crafted URLs that rapidly use all available memory in Jenkins, potentially leading to out of memory errors. Jenkins 2.275, LTS 2.263.2 limits the maximum size of graphs to an area of 10 million pixels. If a larger size is requested, the default size for the graph
O3 Security · Impact-Aware SCA

Is CVE-2021-21607 in your dependencies?

O3 Security finds CVE-2021-21607 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

Scan my dependencies How O3 SCA works
CVE-2021-21607: jenkins-core (Medium 6.5) | O3 Security