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Medium

Jetty Utility Servlets ConcatServlet Double Decoding Information Disclosure Vulnerability

  • Disclosed: 10.06.2021
  • Updated: 11.10.2026 13:19

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 software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
Java / Kotlin (Maven) org.eclipse.jetty:jetty-servlets < 9.4.41, >= 10.0.0, < 10.0.3, >= 11.0.0, < 11.0.3 9.4.41, 10.0.3, 11.0.3

References

CVSS score 5.3/10
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Weakness (CWE)
CWE-200
Platform
Java / Kotlin (Maven)
Package
org.eclipse.jetty:jetty-servlets
Disclosed
10.06.2021
Updated
11.10.2026 13:19

Sources and licenses

OSV / GitHub Advisory Database - GHSA-gwcr-j4wh-j3cq - CC BY 4.0

Vulnerability history: org.eclipse.jetty:jetty-servlets

All published vulnerabilities of this package (Java / Kotlin (Maven)), newest first. Shows whether this is a one-off slip or a package that needs watching.

Total entries
4
First → latest
06.2021 10.2024
Without a fix
0
Exploited in attacks
0

Severity breakdown

  • Medium 2
  • Low 2

Disclosures per year

  1. Eclipse Jetty's PushSessionCacheFilter can cause remote DoS attacks
    Low · 3.1 CVE-2024-6762 >= 10.0.0, < 10.0.18, >= 11.0.0, < 11.0.18, >= 12.0.0, < 12.0.4 10.0.18, 11.0.18, 12.0.4
  2. Eclipse Jetty has a denial of service vulnerability on DosFilter
    Medium · 5.3 CVE-2024-9823 >= 9.0.0, < 9.4.54, >= 10.0.0, < 10.0.18, >= 11.0.0, < 11.0.18 9.4.54, 10.0.18, 11.0.18
  3. Jetty vulnerable to errant command quoting in CGI Servlet
    Low · 3.5 CVE-2023-36479 >= 9.0.0, < 9.4.52, >= 10.0.0, < 10.0.16, >= 11.0.0, < 11.0.16 9.4.52, 10.0.16, 11.0.16
  4. Jetty Utility Servlets ConcatServlet Double Decoding Information Disclosure Vulnerability this entry
    Medium · 5.3 CVE-2021-28169 < 9.4.41, >= 10.0.0, < 10.0.3, >= 11.0.0, < 11.0.3 9.4.41, 10.0.3, 11.0.3

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