How severe is CVE-2021-28164?

CVE-2021-28164 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-2021-28164?

CVE-2021-28164 affects the following packages: org.eclipse.jetty:jetty-webapp (Maven). Ecosystems affected: Maven.

How do I fix CVE-2021-28164?

Update org.eclipse.jetty:jetty-webapp to version 9.4.39 or later. Run your dependency manager's update command and verify no transitive dependencies pin the vulnerable version. Use O3 Security's SCA scanner to confirm the fix is applied across your entire dependency tree.

Is CVE-2021-28164 actively exploited in the wild?

Yes. There are 3 known exploit references for CVE-2021-28164, including 1 documented proof-of-concept exploit on Exploit-DB and 2 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2021-28164?

CVE-2021-28164 has an EPSS (Exploit Prediction Scoring System) score of 93.5%, 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.

Is there exploit tooling available for CVE-2021-28164?

A Nuclei detection template exists for CVE-2021-28164, 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-2021-28164 published, and has it been updated?

CVE-2021-28164 was published on April 1, 2021 and was last updated on April 10, 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

CVE-2021-28164

MEDIUM

Authorization Before Parsing and Canonicalization in jetty

Also known asGHSA-v7ff-8wcx-gmc5

Published

Apr 1, 2021

Updated

Apr 10, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

3 known

EPSS Exploitation Probability

via FIRST.org ↗

93.5%probability of exploitation in next 30 days

Very High Risk100th percentile0.00%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

1 pkg affected

☕org.eclipse.jetty:jetty-webapp

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

In Eclipse Jetty 9.4.37.v20210219 to 9.4.38.v20210224, the default compliance mode allows requests with URIs that contain %2e or %2e%2e segments to access protected resources within the WEB-INF directory. For example a request to /context/%2e/WEB-INF/web.xml can retrieve the web.xml file. This can reveal sensitive information regarding the implementation of a web application.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.eclipse.jetty:jetty-webapp`	≥ 9.4.37&&< 9.4.39	9.4.39

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

EDB-50438webappsjava

Jetty 9.4.37.v20210219 - Information Disclosure

by Mayank Deshmukh · Oct 22, 2021

Exploit-DB Source

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2021-28164 in your stack?

O3 detects CVE-2021-28164 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my stack How O3 SCA works

CVSS Score

5.3/10

CVSS v3 base score

Vector breakdown

AV:Attack Vector

Network

AC:Attack Complexity

Low

PR:Privileges Required

None

UI:User Interaction

None

S:Scope

Unchanged

C:Confidentiality

Low

I:Integrity

None

A:Availability

None

Raw vector

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

Weaponization

OpenSSF Scorecard

Package health score

jetty.project

8.0/10

Maintained10/10

Code-Review10/10

Branch-Protection4/10

Assessed Jun 8, 2026

Timeline

Disclosed

Apr 1, 2021

First exploit

Oct 22, 2021

Last updated

Apr 10, 2026

Identifiers

CVE-2021-28164

GHSA-v7ff-8wcx-gmc5

Data from OSV.dev, enriched by O3 Security. Refreshed hourly.