CVE-2021-28169: Jetty servlets Jetty Utility Servlets ConcatServlet Double Vulnerability

Q: What is CVE-2021-28169?

CVE-2021-28169 is a security vulnerability in Jetty servlets involving Jetty Utility Servlets ConcatServlet Double Decoding Information Disclosure Vulnerability under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor.

Q: Which Jetty servlets versions are affected?

Affected versions include releases prior to 9.4.41, 10.0.3, 11.0.3 across affected packages: org.eclipse.jetty:jetty-servlets.

Q: What version fixes CVE-2021-28169?

Upgrading to 9.4.41, 10.0.3, 11.0.3 (or the latest patched release for your respective branch) resolves the vulnerability.

Q: Is jetty-servlets affected?

Yes, org.eclipse.jetty:jetty-servlets is affected in releases prior to 9.4.41, 10.0.3, 11.0.3. Upgrade your dependency to 9.4.41, 10.0.3, 11.0.3 or later.

Q: What is the CVSS score of CVE-2021-28169?

CVE-2021-28169 has a CVSS v3.1 base score of 5.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.

Q: What CWE is associated with CVE-2021-28169?

CVE-2021-28169 is classified under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor (The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.).

Q: How can I check Maven dependencies for CVE-2021-28169?

Run the dependency tree command: 'mvn dependency:tree -Dincludes=org.eclipse.jetty'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.

MODERATE

Advisory Identifier: GHSA-gwcr-j4wh-j3cq

CVSS 5.3

CWE-200

Published 2021-06-10

Advisory Summary

CVE-2021-28169 is a MODERATE (CVSS 5.3) jetty utility servlets concatservlet double vulnerability (CWE-200: Exposure of Sensitive Information to an Unauthorized Actor) affecting Jetty servlets libraries in the Maven ecosystem. The issue involves jetty utility servlets concatservlet double decoding information disclosure vulnerability. Remediation is available by upgrading affected packages to version 9.4.41, 10.0.3, 11.0.3.

CVE-2021-28169 at a Glance

CVE Identifier CVE-2021-28169

GHSA Identifier GHSA-gwcr-j4wh-j3cq

Severity MODERATE

CVSS v3.1 Base Score 5.3

CWE Classification CWE-200: Exposure of Sensitive Information to an Unauthorized Actor

Affected Product Jetty servlets

Package Ecosystem Maven

Published Date 2021-06-10

Last Updated 2022-02-08

Security Impact

CVSS: 5.3

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N).

Attack Vector Network (AV:N)

Attack Complexity Low (AC:L)

Privileges Required None (PR:N)

User Interaction None (UI:N)

Scope Unchanged (S:U)

Confidentiality Low (C:L)

Integrity None (I:N)

Availability None (A:N)

How to Fix CVE-2021-28169

To remediate this vulnerability, upgrade all affected Jetty servlets dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

org.eclipse.jetty:jetty-servlets fixed: 9.4.41

<dependency>
    <groupId>org.eclipse.jetty</groupId>
    <artifactId>jetty-servlets</artifactId>
    <version>9.4.41</version>
</dependency>

org.eclipse.jetty:jetty-servlets fixed: 10.0.3

<dependency>
    <groupId>org.eclipse.jetty</groupId>
    <artifactId>jetty-servlets</artifactId>
    <version>10.0.3</version>
</dependency>

org.eclipse.jetty:jetty-servlets fixed: 11.0.3

<dependency>
    <groupId>org.eclipse.jetty</groupId>
    <artifactId>jetty-servlets</artifactId>
    <version>11.0.3</version>
</dependency>

Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release:

mvn dependency:tree -Dincludes=org.eclipse.jetty

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2021-28169, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=org.eclipse.jetty

Analyze the terminal output to locate any version of Jetty servlets in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 9.4.41), your application is affected.

Note: The mvn dependency:tree -Dincludes=org.eclipse.jetty command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor, where the product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. In Jetty servlets, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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`](https://github.com/eclipse/jetty.project/blob/4204526d2fdad355e233f6bf18a44bfe028ee00b/jetty-servlets/src/main/java/org/eclipse/jetty/servlets/ConcatServlet.java) and/or the [`WelcomeFilter`](https://github.com/eclipse/jetty.project/blob/4204526d2fdad355e233f6bf18a44bfe028ee00b/jetty-servlets/src/main/java/org/eclipse/jetty/servlets/WelcomeFilter.java) by using the code from the latest version of Jetty.

CVE-2021-28169 Affected Jetty servlets Versions

3 component(s)

Fixed Versions:

9.4.4110.0.311.0.3

Product / Package	Ecosystem	Affected Versions	Fixed Version
org.eclipse.jetty:jetty-servlets maven/org.eclipse.jetty/jetty-servlets	Maven	< 9.4.41	9.4.41
org.eclipse.jetty:jetty-servlets maven/org.eclipse.jetty/jetty-servlets	Maven	≥ 10.0.0 < 10.0.3	10.0.3
org.eclipse.jetty:jetty-servlets maven/org.eclipse.jetty/jetty-servlets	Maven	≥ 11.0.0 < 11.0.3	11.0.3

References

GitHub Advisory / Wiki ADVISORY

https://github.com/eclipse/jetty.project/security/advisories/GHSA-gwcr-j4wh-j3cq

NVD — CVE-2021-28169 NVD

https://nvd.nist.gov/vuln/detail/CVE-2021-28169

Jetty servlets Security Information SECURITY

https://www.oracle.com/security-alerts/cpuoct2021.html

Jetty servlets Security Information SECURITY

https://www.oracle.com/security-alerts/cpujan2022.html

Jetty servlets Security Information SECURITY

https://www.oracle.com/security-alerts/cpuapr2022.html

Jetty servlets Security Information SECURITY

https://www.debian.org/security/2021/dsa-4949

Jetty servlets Security Information SECURITY

https://security.netapp.com/advisory/ntap-20210727-0009

lists.debian.org/debian-lts-announce... WEB

https://lists.debian.org/debian-lts-announce/2021/06/msg00017.html

lists.apache.org/thread.html/rfff6ff... WEB

https://lists.apache.org/thread.html/rfff6ff8ffb31e8a32619c79774def44b6ffbb037c128c5ad3eab7171@%3Cissues.zookeeper.apache.org%3E

lists.apache.org/thread.html/rf36f11... WEB

https://lists.apache.org/thread.html/rf36f1114e84a3379b20587063686148e2d5a39abc0b8a66ff2a9087a@%3Cissues.zookeeper.apache.org%3E

lists.apache.org/thread.html/ref1c16... WEB

https://lists.apache.org/thread.html/ref1c161a1621504e673f9197b49e6efe5a33ce3f0e6d8f1f804fc695@%3Cjira.kafka.apache.org%3E

lists.apache.org/thread.html/rddbb4f... WEB

https://lists.apache.org/thread.html/rddbb4f8d5db23265bb63d14ef4b3723b438abc1589f877db11d35450@%3Cissues.zookeeper.apache.org%3E

lists.apache.org/thread.html/rd5b523... WEB

https://lists.apache.org/thread.html/rd5b52362f5edf98e0dcab6541a381f571cccc05ad9188e793af688f3@%3Cjira.kafka.apache.org%3E

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https://lists.apache.org/thread.html/rbefa055282d52d6b58d29a79fbb0be65ab0a38d25f00bd29eaf5e6fd@%3Cnotifications.zookeeper.apache.org%3E

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https://lists.apache.org/thread.html/r91e34ff61aff8fd25a3f2a21539597c6ef7589a31c199b0a9546477c@%3Cjira.kafka.apache.org%3E

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lists.apache.org/thread.html/r33eb06... WEB

https://lists.apache.org/thread.html/r33eb06b05afbc7df28d31055cae0cb3fd36cab808c884bf6d680bea5@%3Cdev.zookeeper.apache.org%3E

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https://lists.apache.org/thread.html/r32b0b640ad2be3b858f0af51c68a7d5c5a66a462c8bbb93699825cd3@%3Cissues.zookeeper.apache.org%3E

lists.apache.org/thread.html/r296789... WEB

https://lists.apache.org/thread.html/r29678972c3f8164b151fd7a5802785d402e530c09870a82ffc7681a4@%3Cdev.kafka.apache.org%3E

lists.apache.org/thread.html/r284de9... WEB

https://lists.apache.org/thread.html/r284de9c5399486dfff12ab9e7323ca720dd7019a9a3e11c8510a7140@%3Cjira.kafka.apache.org%3E

lists.apache.org/thread.html/r2721ab... WEB

https://lists.apache.org/thread.html/r2721aba31a8562639c4b937150897e24f78f747cdbda8641c0f659fe@%3Cusers.kafka.apache.org%3E

lists.apache.org/thread.html/r234f64... WEB

https://lists.apache.org/thread.html/r234f6452297065636356f43654cdacef565b8f9ceb0e0c07ffb8c73b@%3Cdev.kafka.apache.org%3E

lists.apache.org/thread.html/r04a4b4... WEB

https://lists.apache.org/thread.html/r04a4b4553a23aff26f42635a6ae388c3b162aab30a88d12e59d05168@%3Cjira.kafka.apache.org%3E

Jetty servlets Source Repository REPOSITORY

https://github.com/eclipse/jetty.project

Frequently Asked Questions

What is CVE-2021-28169?

CVE-2021-28169 is a security vulnerability in Jetty servlets involving Jetty Utility Servlets ConcatServlet Double Decoding Information Disclosure Vulnerability under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor.

Which Jetty servlets versions are affected?

Affected versions include releases prior to 9.4.41, 10.0.3, 11.0.3 across affected packages: org.eclipse.jetty:jetty-servlets.

What version fixes CVE-2021-28169?

Upgrading to 9.4.41, 10.0.3, 11.0.3 (or the latest patched release for your respective branch) resolves the vulnerability.

Is jetty-servlets affected?

Yes, org.eclipse.jetty:jetty-servlets is affected in releases prior to 9.4.41, 10.0.3, 11.0.3. Upgrade your dependency to 9.4.41, 10.0.3, 11.0.3 or later.

What is the CVSS score of CVE-2021-28169?

CVE-2021-28169 has a CVSS v3.1 base score of 5.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.

What CWE is associated with CVE-2021-28169?

CVE-2021-28169 is classified under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor (The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.).

How can I check Maven dependencies for CVE-2021-28169?

Run the dependency tree command: 'mvn dependency:tree -Dincludes=org.eclipse.jetty'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.

Machine-readable OSV JSON OSV v1.5 Schema

Normalized schema output

View Raw JSON

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  "id" : "GHSA-gwcr-j4wh-j3cq",
  "modified" : "2022-02-08T21:23:08Z",
  "published" : "2021-06-10T15:43:22Z",
  "aliases" : [ "CVE-2021-28169" ],
  "summary" : "Jetty Utility Servlets ConcatServlet Double Decoding Information Disclosure Vulnerability",
  "details" : "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.\n\nThis 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.\n\n### Impact\nThis affects all versions of `ConcatServlet` and `WelcomeFilter` in versions before 9.4.41, 10.0.3 and 11.0.3.\n\n### Workarounds\n\nIf you cannot update to the latest version of Jetty, you can instead deploy your own version of the [`ConcatServlet`](https://github.com/eclipse/jetty.project/blob/4204526d2fdad355e233f6bf18a44bfe028ee00b/jetty-servlets/src/main/java/org/eclipse/jetty/servlets/ConcatServlet.java) and/or the [`WelcomeFilter`](https://github.com/eclipse/jetty.project/blob/4204526d2fdad355e233f6bf18a44bfe028ee00b/jetty-servlets/src/main/java/org/eclipse/jetty/servlets/WelcomeFilter.java) by using the code from the latest version of Jetty.\n",
  "severity" : [ {
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  "database_specific" : {
    "cwe_ids" : [ "CWE-200" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-06-09T20:02:50Z",
    "nvd_published_at" : "2021-06-09T02:15:00Z"
  }
}

CVSS V3

5.3 MODERATE

Attack Vector Network (AV:N)

Attack Complexity Low (AC:L)

Privileges Required None (PR:N)

User Interaction None (UI:N)

Scope Unchanged (S:U)

Confidentiality Low (C:L)

Integrity None (I:N)

Availability None (A:N)

Vector String

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Advisory Metadata

Source ID: GHSA-gwcr-j4wh-j3cq
Schema Version: 1.4.0
Published: 2021-06-10 15:43
Last Modified: 2022-02-08 21:23
Database Record File: advisories/github-reviewed/2021/06/GHSA-gwcr-j4wh-j3cq/GHSA-gwcr-j4wh-j3cq.json