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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
Updated
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed
Exploitation data as of Nov 5, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.5%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs74th percentile — riskier than 74% of all scored CVEsHighest risk
0.00%0.65%1.31%1.96%0.3%1.5%May 26Sep 26Nov 26

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

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

Affected Products

1 product · 2 configurations
Application
jenkinsjenkins
≤ 2.274
range

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

    Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

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

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CVE-2021-21607: jenkins-core — Fixed in 2.263.2