NIST deprecates RSA-2048 from 2030. Find every one of them before attackers do.
☕
☕ Maven
Not in CISA KEV
CRITICAL severity

CVE-2021-21690 — jenkins-core

CRITICALFix: jenkinsci/jenkins@104c751

CVE-2021-21690 is a critical-severity (CVSS 9.8) Path Traversal 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.

Multiple vulnerabilities allow bypassing path filtering of agent-to-controller access control in Jenkins

Also known asBIT-jenkins-2021-21690GHSA-97c3-w9cr-6qc2
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 ↗
2.5%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs85th percentile — riskier than 85% of all scored CVEsHighest risk
0.00%1.05%2.09%3.14%0.5%2.5%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

The agent-to-controller security subsystem limits which files on the Jenkins controller can be accessed by agent processes.

Multiple vulnerabilities in the file path filtering implementation of Jenkins 2.318 and earlier, LTS 2.303.2 and earlier allow agent processes to read and write arbitrary files on the Jenkins controller file system, and obtain some information about Jenkins controller file systems.

SECURITY-2486 / CVE-2021-21690: Agent processes are able to completely bypass file path filtering by wrapping the file operation in an agent file path.

We expect that most of these vulnerabilities have been present since SECURITY-144 was addressed in the 2014-10-30 security advisory.

Jenkins 2.319, LTS 2.303.3 addresses these security vulnerabilities.

SECURITY-2486 / CVE-2021-21690: Agent processes are no longer able to completely bypass file path filtering by wrapping the file operation in an agent file path.

As some common operations are now newly subject to access control, it is expected that plugins sending commands from agents to the controller may start failing. Additionally, the newly introduced path canonicalization means that instances using a custom builds directory (Java system property jenkins.model.Jenkins.buildsDir) or partitioning JENKINS_HOME using symbolic links may fail access control checks. See the documentation for how to customize the configuration in case of problems.

If you are unable to immediately upgrade to Jenkins 2.319, LTS 2.303.3, you can install the Remoting Security Workaround Plugin. It will prevent all agent-to-controller file access using FilePath APIs. Because it is more restrictive than Jenkins 2.319, LTS 2.303.3, more plugins are incompatible with it. Make sure to read the plugin documentation before installing it.

Affected Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
☕Mavenorg.jenkins-ci.main:jenkins-coreall versions2.303.3org.jenkins-ci.main:jenkins-core:2.303.3
☕Mavenorg.jenkins-ci.main:jenkins-core≥ 2.304&&< 2.3192.319org.jenkins-ci.main:jenkins-core:2.319

Affected Products

1 product · 2 configurations
Application
jenkinsjenkins
< 2.319
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 2.303.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-21690 is resolved across your whole dependency graph.

  3. Workarounds

    Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.

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 HatImportant
Workaround published by Red Hat
Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.
Source: Red Hat security advisory for CVE-2021-21690 (CC BY 4.0)
ProductFixed inAdvisory
Red Hat OpenShift Container Platform 3.11jenkins-0:2.303.3.1637698110-1.el7RHSA-2021:4827
Red Hat OpenShift Container Platform 4.10jenkins-0:2.319.2.1643288987-1.el8RHSA-2022:0055
Red Hat OpenShift Container Platform 4.6jenkins-0:2.303.3.1637597493-1.el8RHSA-2021:4799
Red Hat OpenShift Container Platform 4.7jenkins-0:2.303.3.1637597018-1.el8RHSA-2021:4801
Red Hat OpenShift Container Platform 4.8jenkins-0:2.303.3.1637596565-1.el8RHSA-2021:4829
Red Hat OpenShift Container Platform 4.9jenkins-0:2.303.3.1637595827-1.el8RHSA-2021:4833

Frequently Asked Questions

The agent-to-controller security subsystem limits which files on the Jenkins controller can be accessed by agent processes. Multiple vulnerabilities in the file path filtering implementation of Jenkins 2.318 and earlier, LTS 2.303.2 and earlier allow agent processes to read and write arbitrary files on the Jenkins controller file system, and obtain some information about Jenkins controller file systems. SECURITY-2486 / CVE-2021-21690: Agent processes are able to completely bypass file path filtering by wrapping the file operation in an agent file path. We expect that most of these vulnerabi
O3 Security · Impact-Aware SCA

Is CVE-2021-21690 in your dependencies?

Find it across Maven, including transitive dependencies.

Scan my dependencies How O3 SCA works
CVE-2021-21690: jenkins-core — Fixed in 2.303.3