Vulnerability · CVE-2021-28169
Eclipse Jetty ConcatServlet Vulnerability
Published Aug 19, 2022 · catalog updated Aug 19, 2022 · Eclipse Jetty ConcatServlet
Patch now
CVE-2021-28169 is in the CISA known-exploited catalog. Confirm Eclipse Jetty ConcatServlet against the vendor advisory and apply that fix. The CVSS score does not change the priority.
Gaps on this record
- The stored product name is a package slug. The name on this page is taken from the title (Eclipse Jetty ConcatServlet).
- No version range is stored. A customer cannot check an installed version against this record.
- Severity
- Unknown—
- Known exploitation
- CISA KEV and VulnCheck KEV
- EPSS
- 78.48%
- Remediation
- Remediation guidance
- Affected products
- vendor eclipse jetty
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 can retrieve the web.xml file. This can reveal sensitive information regarding the implementation of a web application.
Are you affected?
Enter the version you run. The result uses only the ranges stored on this record.
The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.
- vendor eclipse jettyversion unspecified
How to fix CVE-2021-28169
Recommended remediation
Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.
Official advisories
What to do
Three questions, each answered from this record only. Confirm the vendor advisory before you patch.
Should you patch?
CVE-2021-28169 is in the CISA known-exploited catalog. Confirm Eclipse Jetty ConcatServlet against the vendor advisory and apply that fix. The CVSS score does not change the priority.
Which versions are affected?
Affected version ranges are not on this record. Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.
What should an analyst verify?
No weakness class is stored. EPSS 78.48%. The CISA KEV listing is the exploitation evidence. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.
Code
The project this record applies to. Exploit listings stay in References.
No public source repository is identified for this product.
Timeline
Detection, updates, and resolution for this record.
Aug 19, 2022 · VulnCheck KEV
Detected
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 can retrieve the web.xml file. This can reveal sensitive information regarding the implementation of a web application.
Aug 19, 2022 · CISA KEV
Known exploited
Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.
Sources
- CVE.orgVulnerability recordCVE-2021-28169
Official CVE identifier
cve.org - FIRST EPSSExploitation probabilityCVE-2021-28169
30-day exploitation probability 78.5%
first.org - VulnCheck KEVConfirmed exploitationCVE-2021-28169
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 can retrieve the web.xml file. This can reveal sensitive in
vulncheck.com
References
Freshness
Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.