CVE-2020-2103 is a medium-severity (CVSS 5.4) Information Exposure 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 Diagnostic page exposed session cookies
EPSS Exploitation Probability
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
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 shows various technical details about the current user on the /whoAmI page. In a previous fix, the Cookie header value containing the HTTP session ID was redacted. However, user metadata shown on this page could also include the HTTP session ID in Jenkins 2.218 and earlier, LTS 2.204.1 and earlier.
This allows attackers able to exploit a cross-site scripting vulnerability to obtain the HTTP session ID value from this page.
Jenkins 2.219, LTS 2.204.2 no longer prints out the affected user metadata that might contain the HTTP session ID.
Additionally, we also redact values of further authentication-related HTTP headers in addition to Cookie on this page as a hardening.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.jenkins-ci.main:jenkins-core | ≥ 2.205&&< 2.219 | 2.219org.jenkins-ci.main:jenkins-core:2.219 |
| ☕Maven | org.jenkins-ci.main:jenkins-core | all versions | 2.204.2org.jenkins-ci.main:jenkins-core:2.204.2 |
Affected Products
jenkinsjenkinsDetection & 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 2.219 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-2103 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.
How to detect CVE-2020-2103
A community-maintained Nuclei template exists for this CVE. You can scan for it directly:
nuclei -id cve-2020-2103 -u https://target- Template
- Jenkins <=2.218 - Information Disclosure
- Severity
- medium
- Impact
- An attacker can exploit this vulnerability to gain sensitive information from the Jenkins server.
- Remediation
- Upgrade Jenkins to a version higher than 2.218 to mitigate the vulnerability.
Template by ProjectDiscovery nuclei-templates (c-sh0), MIT licensed. View the full template. Scan only systems you are authorised to test.
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 3.11 | atomic-enterprise-service-catalog-1:3.11.170-1.git.1.91db82e.el7 | RHBA-2020:0402 |
| Red Hat OpenShift Container Platform 4.3 | jenkins-0:2.204.2.1583446818-1.el7 | RHBA-2020:0675 |
| Red Hat OpenShift Container Platform 4.4 | openshift4/ose-aws-machine-controllers:v4.4.0-202004261927 | RHBA-2020:0581 |
| Red Hat OpenShift Container Platform 4.5 | openshift4/ose-aws-machine-controllers:v4.5.0-202007012112.p0 | RHBA-2020:2409 |
Frequently Asked Questions
Is CVE-2020-2103 in your dependencies?
Find it across Maven, including transitive dependencies.