How severe is CVE-2021-28169?

CVE-2021-28169 has a CVSS score of 5.3/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2021-28169?

CVE-2021-28169 affects the following packages: org.eclipse.jetty:jetty-servlets (Maven), org.eclipse.jetty:jetty-servlets (Maven), org.eclipse.jetty:jetty-servlets (Maven). Ecosystems affected: Maven.

How do I fix CVE-2021-28169?

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.

How do I detect CVE-2021-28169 in my Maven dependencies?

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.

How do I mitigate CVE-2021-28169 if there is no patch (or I can't update yet)?

Assume what was exposed is already known: rotate any credential, token or key that the affected component could return, restrict the endpoint to callers that genuinely need it, and strip sensitive fields from responses and error output at the boundary rather than relying on the client not to read them.

Is CVE-2021-28169 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-28169 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2021-28169?

CVE-2021-28169 has an EPSS (Exploit Prediction Scoring System) score of 78.5%, placing it in the 100th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. A score above 50% indicates significantly elevated exploitation risk — immediate patching is strongly recommended.

What type of vulnerability is CVE-2021-28169?

CVE-2021-28169 is classified as Information Exposure (CWE-200). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

Is there exploit tooling available for CVE-2021-28169?

A Nuclei detection template exists for CVE-2021-28169, meaning automated scanners can fingerprint it. Public exploit tooling significantly increases real-world risk — prioritize patching and ensure detection coverage. Exploit tooling should only ever be used in isolated, authorized testing environments.

When was CVE-2021-28169 published, and has it been updated?

CVE-2021-28169 was published on June 9, 2021 and was last updated on October 24, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕

☕ Maven

Not in CISA KEV

MEDIUM severity

CVE-2021-28169 — jetty-servlets

MEDIUM

CVE-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

Also known asGHSA-gwcr-j4wh-j3cq

Published

Jun 9, 2021

Updated

Oct 24, 2026

Affected

3 pkgs

Patched

3 / 3

Exploits

None indexed

Exploitation data as of Nov 5, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

78.5%probability of exploitation in next 30 days

Very High Risk0.00%

Lower risk than most CVEs100th percentile — riskier than 100% of all scored CVEsHighest risk

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

3 pkgs affected

☕org.eclipse.jetty:jetty-servlets☕org.eclipse.jetty:jetty-servlets☕org.eclipse.jetty:jetty-servlets

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

Requests to the ConcatServlet and WelcomeFilter are able to access protected resources within the WEB-INF directory. For example a request to the ConcatServlet with a URI of /concat?/%2557EB-INF/web.xml can retrieve the web.xml file. This can reveal sensitive information regarding the implementation of a web application.

This occurs because both ConcatServlet and WelcomeFilter decode the supplied path to verify it is not within the WEB-INF or META-INF directories. It then uses this decoded path to call RequestDispatcher which will also do decoding of the path. This double decoding allows paths with a doubly encoded WEB-INF to bypass this security check.

Impact

This affects all versions of ConcatServlet and WelcomeFilter in versions before 9.4.41, 10.0.3 and 11.0.3.

Workarounds

If you cannot update to the latest version of Jetty, you can instead deploy your own version of the ConcatServlet and/or the WelcomeFilter by using the code from the latest version of Jetty.

Affected Packages

3 total 3 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.eclipse.jetty:jetty-servlets`	all versions	9.4.41`org.eclipse.jetty:jetty-servlets:9.4.41`
☕Maven	`org.eclipse.jetty:jetty-servlets`	≥ 10.0.0&&< 10.0.3	10.0.3`org.eclipse.jetty:jetty-servlets:10.0.3`
☕Maven	`org.eclipse.jetty:jetty-servlets`	≥ 11.0.0&&< 11.0.3	11.0.3`org.eclipse.jetty:jetty-servlets:11.0.3`

Affected Products

8 products · 12 configurations

debian linuxdebian

2 versions

9.010.0

Application

jettyeclipse

≥ 11.0.0 && < 11.0.3

range

Application

active iq unified managernetapp

all

Application

hcinetapp

all

Application

management services for element softwarenetapp

all

Application

snap creator frameworknetapp

all

Detection & mitigation playbook

Open-source dependency

Detect
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
Assume what was exposed is already known: rotate any credential, token or key that the affected component could return, restrict the endpoint to callers that genuinely need it, and strip sensitive fields from responses and error output at the boundary rather than relying on the client not to read them.

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.

Red HatModerate

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

Requests to the `ConcatServlet` and `WelcomeFilter` are able to access protected resources within the `WEB-INF` directory. For example a request to the `ConcatServlet` with a URI of `/concat?/%2557EB-INF/web.xml` can retrieve the web.xml file. This can reveal sensitive information regarding the implementation of a web application. This occurs because both `ConcatServlet` and `WelcomeFilter` decode the supplied path to verify it is not within the `WEB-INF` or `META-INF` directories. It then uses this decoded path to call `RequestDispatcher` which will also do decoding of the path. This double

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