CVE-2021-28169 — jetty-servlets
MEDIUMCVE-2021-28169 is a medium-severity (CVSS 5.3) Information Exposure vulnerability in org.eclipse.jetty:jetty-servlets. EPSS puts its 30-day exploitation probability at 78.5% (100th percentile). A fix is available for org.eclipse.jetty:jetty-servlets — see the affected versions and patch details below.
Jetty Utility Servlets ConcatServlet Double Decoding Information Disclosure Vulnerability
EPSS Exploitation Probability
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-2021-28169 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 377,166 CVEs with a current EPSS score, this one falls in the 50–90% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
org.eclipse.jetty:jetty-servlets☕org.eclipse.jetty:jetty-servlets☕org.eclipse.jetty:jetty-servletsReal-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
For Eclipse Jetty versions <= 9.4.40, <= 10.0.2, <= 11.0.2, it is possible for requests to the ConcatServlet with a doubly encoded path to access protected resources within the WEB-INF directory. For example a request to /concat?/%2557EB-INF/web.xml can retrieve the web.xml file. This can reveal sensitive information regarding the implementation of a web application.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.eclipse.jetty:jetty-servlets | all versions | 9.4.41org.eclipse.jetty:jetty-servlets:9.4.41 |
| ☕Maven | org.eclipse.jetty:jetty-servlets | ≥ 10.0.0&&< 10.0.3 | 10.0.3org.eclipse.jetty:jetty-servlets:10.0.3 |
| ☕Maven | org.eclipse.jetty:jetty-servlets | ≥ 11.0.0&&< 11.0.3 | 11.0.3org.eclipse.jetty:jetty-servlets:11.0.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.eclipse.jetty:jetty-servlets, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.eclipse.jetty:jetty-servlets to 9.4.41 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-28169 is resolved across your whole dependency graph.
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.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2021-28169 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2021-28169. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
How to detect CVE-2021-28169
A community-maintained Nuclei template exists for this CVE. You can scan for it directly:
nuclei -id cve-2021-28169 -u https://target- Template
- Eclipse Jetty ConcatServlet - Information Disclosure
- Severity
- medium
- Impact
- An attacker can exploit this vulnerability to access sensitive information, potentially leading to further attacks or unauthorized access.
- Remediation
- Upgrade to Eclipse Jetty version 9.4.40 or later to mitigate this vulnerability.
Template by ProjectDiscovery nuclei-templates (pikpikcu), 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.
In OpenShift Container Platform (OCP), the hive/presto/hadoop components that comprise the OCP metering stack, ship the vulnerable version of jetty. Since the release of OCP 4.6, the metering product has been deprecated [1], hence the affected components are marked as wontfix. This may be fixed in the future. [1]…
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat AMQ 7.9.0 | jetty-server | RHSA-2021:3700 |
| Red Hat AMQ Streams 1.8.0 | jetty-server | RHSA-2021:3225 |
| Red Hat Fuse 7.10 | jetty | RHSA-2021:5134 |
| Red Hat Integration Camel Quarkus 2 | see advisory | RHSA-2021:4767 |
| Red Hat OpenShift Container Platform 4.9 | jenkins-0:2.289.3.1630554997-1.el8 | RHSA-2021:3758 |
| RHINT Camel-K 1.8.1 | jetty | RHSA-2022:7257 |
Frequently Asked Questions
Is CVE-2021-28169 in your dependencies?
O3 Security finds CVE-2021-28169 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.