How severe is CVE-2016-4003?

CVE-2016-4003 has a CVSS score of 6.1/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2016-4003?

CVE-2016-4003 affects the following packages: org.apache.struts:struts2-core (Maven). Ecosystems affected: Maven.

How do I fix CVE-2016-4003?

Update org.apache.struts:struts2-core to 2.3.28 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2016-4003 is resolved across your whole dependency graph.

How do I detect CVE-2016-4003 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.struts:struts2-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2016-4003 if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is CVE-2016-4003 actively exploited in the wild?

No public exploit code has been indexed for CVE-2016-4003 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2016-4003?

CVE-2016-4003 has an EPSS (Exploit Prediction Scoring System) score of 11.6%, placing it in the 96th 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. This score warrants monitoring and prompt remediation.

What type of vulnerability is CVE-2016-4003?

CVE-2016-4003 is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2016-4003 published, and has it been updated?

CVE-2016-4003 was published on April 12, 2016 and was last updated on October 24, 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

Not in CISA KEV

MEDIUM severity

CVE-2016-4003 — struts2-core

MEDIUMFix: apache/struts@4720f46

CVE-2016-4003 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in org.apache.struts:struts2-core. EPSS puts its 30-day exploitation probability at 11.6% (96th percentile). A fix is available for org.apache.struts:struts2-core — see the affected versions and patch details below.

Cross-site Scripting in Apache Struts

Also known asGHSA-m3x6-9v6h-4g28

Published

Apr 12, 2016

Updated

Oct 24, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 30, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

11.6%probability of exploitation in next 30 days

Moderate Risk0.00%

Lower risk than most CVEs96th percentile — riskier than 96% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

☕org.apache.struts:struts2-core

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

Cross-site scripting (XSS) vulnerability in the URLDecoder function in JRE before 1.8, as used in Apache Struts 2.x before 2.3.28, when using a single byte page encoding, allows remote attackers to inject arbitrary web script or HTML via multi-byte characters in a url-encoded parameter.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.apache.struts:struts2-core`	≥ 2.0.0&&< 2.3.28	2.3.28`org.apache.struts:struts2-core:2.3.28`

Affected Products

1 product · 1 configurations

Application

strutsapache

≥ 2.0.0 && ≤ 2.3.24.1

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.struts:struts2-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.apache.struts:struts2-core to 2.3.28 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2016-4003 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2016-4003 in your dependencies?

Find it across Maven, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

6.1/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Raw vector

CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CWE Classification

CWE-79Cross-site Scripting (XSS)

Weaponization

No Nuclei template, Metasploit module or public proof-of-concept found.

OpenSSF Scorecard

Package health score

struts

8.4/10

Maintained10/10

Code-Review0/10

Dependency-Update-Tool10/10

Branch-ProtectionN/A

Vulnerabilities8/10

Assessed Oct 27, 2026

Timeline

Disclosed

Apr 12, 2016

Last updated

Oct 24, 2026

Identifiers

CVE-2016-4003

GHSA-m3x6-9v6h-4g28

References

Advisorystruts.apache.org · s2 028 Advisorysecurityfocus.com Advisorysecuritytracker.com Advisoryissues.apache.org · WW 4507 Advisorynvd.nist.gov · CVE 2016 4003 Webgithub.com · 4720f46a63caaf9db97ba27dc51ac5ad21e66bdc Webgithub.com · 5421930b49822606792f36653b17d3d95ef106f9 Webgithub.com · 72471d7075681bea52046645ad7aa34e9c53751e Webgithub.com · 76f188406eb9f17a06afcb5f49f0c44d749da0d2 Webgithub.com · a89bbe22cd2461748d595a89a254de888a415e6c Webweb.archive.org Webweb.archive.org Packagegithub.com · struts

Related vulnerabilities

This CVE is medium severity; 8 of 8 other CVEs affecting struts2-core are rated as high or higher (top: critical).

CVE-2025-68493CVE-2025-66675CVE-2025-64775CVE-2024-53677CVE-2023-50164CVE-2023-41835CVE-2023-34396CVE-2023-34149

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedOct 24, 2026