How severe is CVE-2016-4438?

CVE-2016-4438 has a CVSS score of 9.8/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2016-4438?

CVE-2016-4438 affects the following packages: org.apache.struts:struts2-core (Maven), org.apache.struts:struts2-rest-plugin (Maven). Ecosystems affected: Maven.

How do I fix CVE-2016-4438?

Update org.apache.struts:struts2-core to 2.3.29 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2016-4438 is resolved across your whole dependency graph.

How do I detect CVE-2016-4438 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-2016-4438 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2016-4438 actively exploited in the wild?

No public exploit code has been indexed for CVE-2016-4438 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-2016-4438?

CVE-2016-4438 has an EPSS (Exploit Prediction Scoring System) score of 16.7%, placing it in the 97th 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-2016-4438?

CVE-2016-4438 is classified as Improper Input Validation (CWE-20). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2016-4438 published, and has it been updated?

CVE-2016-4438 was published on July 4, 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

CRITICAL severity

CVE-2016-4438 — struts2-core

CRITICALFix: apache/struts@6d7ac40

CVE-2016-4438 is a critical-severity (CVSS 9.8) Improper Input Validation vulnerability in org.apache.struts:struts2-core. EPSS puts its 30-day exploitation probability at 16.7% (97th percentile). A fix is available for org.apache.struts:struts2-core — see the affected versions and patch details below.

Arbitrary code execution in Apache Struts 2

Also known asGHSA-4prj-vw9j-v6pr

Published

Jul 4, 2016

Updated

Oct 24, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Nov 1, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

16.7%probability of exploitation in next 30 days

Moderate Risk0.00%

Lower risk than most CVEs97th percentile — riskier than 97% 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

2 pkgs affected

☕org.apache.struts:struts2-core☕org.apache.struts:struts2-rest-plugin

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

The REST plugin in Apache Struts 2 2.3.19 through 2.3.28.1 allows remote attackers to execute arbitrary code via a crafted expression.

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.apache.struts:struts2-core`	≥ 2.3.19&&< 2.3.29	2.3.29`org.apache.struts:struts2-core:2.3.29`
☕Maven	`org.apache.struts:struts2-rest-plugin`	≥ 2.3.19&&< 2.3.29	2.3.29`org.apache.struts:struts2-rest-plugin:2.3.29`

Affected Products

1 product · 7 configurations

Application

strutsapache

7 versions

2.3.202.3.20.12.3.20.32.3.242.3.24.12.3.24.32.3.28

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 2.3.29 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2016-4438 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

The REST plugin in Apache Struts 2 2.3.19 through 2.3.28.1 allows remote attackers to execute arbitrary code via a crafted expression.

O3 Security · Impact-Aware SCA

Is CVE-2016-4438 in your dependencies?

Find it across Maven, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

9.8/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Raw vector

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

CWE Classification

CWE-20Improper Input Validation

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 31, 2026

Timeline

Disclosed

Jul 4, 2016

Last updated

Oct 24, 2026

Identifiers

CVE-2016-4438

GHSA-4prj-vw9j-v6pr

References

Advisoryjvn.jp · index Advisoryjvndb.jvn.jp · JVNDB 2016 000110 Advisoryoracle.com · cpujul2017 3236622 Advisorysecurityfocus.com Advisorystruts.apache.org · s2 037 Advisorynvd.nist.gov · CVE 2016 4438 Reportbugzilla.redhat.com · show bug.cgi Webgithub.com · 6d7ac40dcede1793a4534a3dc249fd562d495e8c Webgithub.com · 76eb8f38a33ad0f1f48464ee1311559c8d52dd6d Webgithub.com · c9c21378f2fb2ff21355c128c45e106ebd87ad7c Webgithub.com · deefeffd11425f0cd0b797cd86a9b3550234262b Packagegithub.com · struts

Related vulnerabilities

This CVE is critical severity; 2 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

CVE-2016-4438 — struts2-core

EPSS Exploitation Probability

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

Description

Affected Packages

Affected Products

Detection & mitigation playbook

Detect

Fix

Workarounds

Frequently Asked Questions

Is CVE-2016-4438 in your dependencies?