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CVE-2021-28169

MEDIUM
Published 2021-06-09T01:55:09
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CVSS Score

V3.1
5.3
/10
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Base Score Metrics
Exploitability: N/A Impact: N/A

EPSS Score

v2025.03.14
0.924
probability
of exploitation in the wild

There is a 92.4% chance that this vulnerability will be exploited in the wild within the next 30 days.

Updated: 2025-06-25
Exploit Probability
Percentile: 0.997
Higher than 99.7% of all CVEs

Attack Vector Metrics

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED

Impact Metrics

Confidentiality
LOW
Integrity
NONE
Availability
NONE

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.

Understanding This Vulnerability

This Common Vulnerabilities and Exposures (CVE) entry provides detailed information about a security vulnerability that has been publicly disclosed. CVEs are standardized identifiers assigned by MITRE Corporation to track and catalog security vulnerabilities across software and hardware products.

The severity rating (MEDIUM) indicates the potential impact of this vulnerability based on the CVSS (Common Vulnerability Scoring System) framework. Higher severity ratings typically indicate vulnerabilities that could lead to more significant security breaches if exploited. Security teams should prioritize remediation efforts based on severity, exploit availability, and the EPSS (Exploit Prediction Scoring System) score, which predicts the likelihood of exploitation in the wild.

If this vulnerability affects products or systems in your infrastructure, we recommend reviewing the affected products section, checking for available patches or updates from vendors, and implementing recommended workarounds or solutions until a permanent fix is available. Organizations should also monitor security advisories and threat intelligence feeds for updates about active exploitation of this vulnerability.

Available Exploits

Eclipse Jetty ConcatServlet - Information Disclosure

Eclipse Jetty through 9.4.40, through 10.0.2, and through 11.0.2 is susceptible to information disclosure. Requests to the ConcatServlet with a doubly encoded path can access protected resources within the WEB-INF directory, thus enabling an attacker to potentially obtain sensitive information, modify data, and/or execute unauthorized administrative operations in the context of the affected site.

ID: CVE-2021-28169
Author: pikpikcu Medium

Related News

No news articles found for this CVE.

Affected Products

References

https://github.com/eclipse/jetty.project/security/advisories/GHSA-gwcr-j4wh-j3cq (CNA)
https://lists.apache.org/thread.html/r2721aba31a8562639c4b937150897e24f78f747cdbda8641c0f659fe%40%3Cusers.kafka.apache.org%3E (CNA)
https://lists.debian.org/debian-lts-announce/2021/06/msg00017.html (CNA)
https://lists.apache.org/thread.html/ref1c161a1621504e673f9197b49e6efe5a33ce3f0e6d8f1f804fc695%40%3Cjira.kafka.apache.org%3E (CNA)
https://lists.apache.org/thread.html/r29678972c3f8164b151fd7a5802785d402e530c09870a82ffc7681a4%40%3Cdev.kafka.apache.org%3E (CNA)
https://lists.apache.org/thread.html/r04a4b4553a23aff26f42635a6ae388c3b162aab30a88d12e59d05168%40%3Cjira.kafka.apache.org%3E (CNA)
https://lists.apache.org/thread.html/rd5b52362f5edf98e0dcab6541a381f571cccc05ad9188e793af688f3%40%3Cjira.kafka.apache.org%3E (CNA)
https://lists.apache.org/thread.html/r284de9c5399486dfff12ab9e7323ca720dd7019a9a3e11c8510a7140%40%3Cjira.kafka.apache.org%3E (CNA)
https://lists.apache.org/thread.html/r234f6452297065636356f43654cdacef565b8f9ceb0e0c07ffb8c73b%40%3Cdev.kafka.apache.org%3E (CNA)
https://lists.apache.org/thread.html/r91e34ff61aff8fd25a3f2a21539597c6ef7589a31c199b0a9546477c%40%3Cjira.kafka.apache.org%3E (CNA)
https://lists.apache.org/thread.html/rb1292d30462b9baedea7c5d9594fc75990d9aa0ec223b48054ca9c25%40%3Cjira.kafka.apache.org%3E (CNA)
https://www.debian.org/security/2021/dsa-4949 (CNA)
https://lists.apache.org/thread.html/rfff6ff8ffb31e8a32619c79774def44b6ffbb037c128c5ad3eab7171%40%3Cissues.zookeeper.apache.org%3E (CNA)
https://lists.apache.org/thread.html/r32b0b640ad2be3b858f0af51c68a7d5c5a66a462c8bbb93699825cd3%40%3Cissues.zookeeper.apache.org%3E (CNA)
https://lists.apache.org/thread.html/rf36f1114e84a3379b20587063686148e2d5a39abc0b8a66ff2a9087a%40%3Cissues.zookeeper.apache.org%3E (CNA)
https://lists.apache.org/thread.html/rddbb4f8d5db23265bb63d14ef4b3723b438abc1589f877db11d35450%40%3Cissues.zookeeper.apache.org%3E (CNA)
https://lists.apache.org/thread.html/r33eb06b05afbc7df28d31055cae0cb3fd36cab808c884bf6d680bea5%40%3Cdev.zookeeper.apache.org%3E (CNA)
https://lists.apache.org/thread.html/r67c4f90658fde875521c949448c54c98517beecdc7f618f902c620ec%40%3Cissues.zookeeper.apache.org%3E (CNA)
https://www.oracle.com/security-alerts/cpuoct2021.html (CNA)
https://lists.apache.org/thread.html/r8a1a332899a1f92c8118b0895b144b27a78e3f25b9d58a34dd5eb084%40%3Cnotifications.zookeeper.apache.org%3E (CNA)
https://lists.apache.org/thread.html/rbefa055282d52d6b58d29a79fbb0be65ab0a38d25f00bd29eaf5e6fd%40%3Cnotifications.zookeeper.apache.org%3E (CNA)
https://security.netapp.com/advisory/ntap-20210727-0009/ (CNA)
https://www.oracle.com/security-alerts/cpujan2022.html (CNA)
https://www.oracle.com/security-alerts/cpuapr2022.html (CNA)

GitHub Security Advisories

Community-driven vulnerability intelligence from GitHub

✓ GitHub Reviewed MODERATE

Jetty Utility Servlets ConcatServlet Double Decoding Information Disclosure Vulnerability

GHSA-gwcr-j4wh-j3cq

Advisory 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. 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.

Affected Packages

Maven org.eclipse.jetty:jetty-servlets
ECOSYSTEM: ≥0 <9.4.41
Maven org.eclipse.jetty:jetty-servlets
ECOSYSTEM: ≥10.0.0 <10.0.3
Maven org.eclipse.jetty:jetty-servlets
ECOSYSTEM: ≥11.0.0 <11.0.3

CVSS Scoring

CVSS Score

5.0

CVSS Vector

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

References

Advisory provided by GitHub Security Advisory Database. Published: June 10, 2021, Modified: February 8, 2022

References

Published: 2021-06-09T01:55:09
Last Modified: 2024-08-03T21:40:12.267Z
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