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MEDIUM severity

CVE-2020-2105 — jenkins-core

MEDIUMFix: jenkinsci/jenkins@639ade5

CVE-2020-2105 is a medium-severity (CVSS 5.4) CWE-1021 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.

Jenkins REST APIs vulnerable to clickjacking

Also known asBIT-jenkins-2020-2105GHSA-7xp8-7wqx-5hqx
Published
Updated
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed
Exploitation data as of Nov 2, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.8%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs79th percentile — riskier than 79% of all scored CVEsHighest risk
0.00%0.78%1.57%2.35%0.3%1.8%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 2.218 and earlier, LTS 2.204.1 and earlier does not serve the X-Frame-Options: deny HTTP header on REST API responses to protect against clickjacking attacks. An attacker could exploit this by routing the victim through a specially crafted web page that embeds a REST API endpoint in an iframe and tricking the user into performing an action which would allow for the attacker to learn the content of that REST API endpoint.

Jenkins 2.219, LTS 2.204.2 now adds the X-Frame-Options: deny HTTP header to REST API responses, which prevents these types of clickjacking attacks.

Affected Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
☕Mavenorg.jenkins-ci.main:jenkins-coreall versions2.204.2org.jenkins-ci.main:jenkins-core:2.204.2
☕Mavenorg.jenkins-ci.main:jenkins-core≥ 2.205&&< 2.2192.219org.jenkins-ci.main:jenkins-core:2.219

Affected Products

1 product · 2 configurations
Application
jenkinsjenkins
≤ 2.218
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 2.204.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-2105 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.

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 HatLow
ProductFixed inAdvisory
Red Hat OpenShift Container Platform 3.11atomic-enterprise-service-catalog-1:3.11.170-1.git.1.91db82e.el7RHBA-2020:0402
Red Hat OpenShift Container Platform 4.3jenkins-0:2.204.2.1583446818-1.el7RHBA-2020:0675
Red Hat OpenShift Container Platform 4.4openshift4/ose-aws-machine-controllers:v4.4.0-202004261927RHBA-2020:0581
Red Hat OpenShift Container Platform 4.5openshift4/ose-aws-machine-controllers:v4.5.0-202007012112.p0RHBA-2020:2409

Frequently Asked Questions

Jenkins 2.218 and earlier, LTS 2.204.1 and earlier does not serve the `X-Frame-Options: deny` HTTP header on REST API responses to protect against clickjacking attacks. An attacker could exploit this by routing the victim through a specially crafted web page that embeds a REST API endpoint in an iframe and tricking the user into performing an action which would allow for the attacker to learn the content of that REST API endpoint. Jenkins 2.219, LTS 2.204.2 now adds the `X-Frame-Options: deny` HTTP header to REST API responses, which prevents these types of clickjacking attacks.
O3 Security · Impact-Aware SCA

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CVE-2020-2105: jenkins-core — Fixed in 2.204.2