Apache Struts is an open-source Java web application framework used to build server-side applications. It provides structured support for request handling, view rendering, and form processing. Because it is widely deployed in internet-facing systems, vulnerabilities in Struts can create broad and fast-moving exposure across enterprise application estates.
How Apache Struts Fits Into Web Application Security
Apache Struts is best understood as application infrastructure that sits directly on the request path, which means its security posture affects how user input is handled, validated, and turned into server-side actions. Because Struts is deployed in internet-facing Java applications, flaws in the framework can have outsized impact across many downstream applications.
That makes Struts less about a single page or feature and more about the security of the application plumbing around request processing, form binding, action execution, and view rendering. When that plumbing is weak, attackers often gain a way to influence server behaviour without needing deep access to the application itself.
Why Struts Vulnerabilities Spread So Quickly
Framework vulnerabilities are especially dangerous because the same code path is reused across many applications. A weakness in Struts can therefore become a repeatable exploitation path in multiple deployments, particularly where patching is delayed or where older applications continue to depend on the vulnerable component.
This is why Struts has historically been associated with high-consequence exposure: the framework is not just a library in the background, it is part of the trust boundary. If request parsing, OGNL expression handling, or action dispatch is compromised, the result can be server-side execution, data exposure, or full application takeover depending on the flaw.
For a broader treatment of how this kind of platform-wide weakness changes risk across enterprise estates, the NIST Cybersecurity Framework 2.0 is useful for framing governance, detection, response, and recovery around shared application dependencies.
Common Security Failure Modes in Struts-Based Applications
The main failure modes in Struts are the same ones that make web frameworks attractive to attackers: unsafe input handling, vulnerable expression evaluation, insecure plugin or extension usage, and delayed remediation of known issues. These are not abstract implementation details, they are the places where attacker-controlled data can become code-adjacent behaviour.
Struts applications can also inherit risk from surrounding controls, including weak patch discipline, poor inventory of deployed framework versions, and reliance on outdated example code that has not been updated to reflect modern secure defaults. In practice, the security outcome often depends as much on operational hygiene as on the framework itself.
Guidance on secure coding and input handling in the OWASP Cheat Sheet Series and the attack-focused coverage in the OWASP API Security Top 10 are both useful reference points when Struts is used to expose application actions and backend services.
What Practitioners Need to Understand About Exposure and Remediation
Struts becomes a security priority when it is part of a live, externally reachable application estate, not when it is merely present in source control. The practical question is whether the deployed version is current, whether vulnerable action paths still exist, and whether the application has compensating controls around authentication, input validation, and patch rollback.
One useful way to think about Struts risk is that framework-level compromise is usually systemic rather than local. A single vulnerable component may affect many routes, many pages, and many business processes at once, so remediation has to be treated as an application-wide event rather than a narrow bug fix.
For teams that need to prioritise exposure management, FIRST EPSS can help rank exploitability, while CIS Benchmarks remain useful for hardening the underlying runtime and host environment that Struts depends on.
Risk and Threat Considerations
Struts has a material threat profile because known framework weaknesses have historically been attractive to attackers seeking remote code execution, data theft, and broad compromise of internet-facing applications. The main risk is not just that one application fails, but that many applications built on the same vulnerable framework may fail in the same way.
Failure mechanism: attackers exploit a framework-level flaw in request handling or expression processing, then use the resulting server-side control to pivot into application logic, sensitive data, or the host environment.
Impact: compromise can spread quickly across estates that reuse the same Struts version, creating systemic exposure, service disruption, and potentially large-scale breach consequences before defenders identify the vulnerable deployment.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
OWASP Non-Human Identity Top 10 and MITRE ATT&CK address the attack and risk surface, while NIST CSF 2.0 and CIS Controls v8 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST CSF 2.0 | GV.SC — Cyber Supply Chain Risk Management | Struts is a reused application dependency whose version and exposure must be governed. |
| PR.IP — Information Protection Processes and Procedures | Struts security depends on timely patching, secure deployment, and maintenance routines. | |
| DE.CM — Continuous Monitoring | Internet-facing Struts deployments need monitoring for exposure and suspicious framework abuse. | |
| Recommendation — Track Struts as a managed dependency and verify patch status across the application estate. Apply disciplined patch and change processes to remove vulnerable Struts versions quickly. Monitor Struts-backed applications for exploit activity, anomalous requests, and vulnerable versions. | ||
| CIS Controls v8 | CIS 7 — Continuous Vulnerability Management | Struts vulnerabilities require discovery, prioritisation, and rapid remediation across assets. |
| CIS 16 — Application Software Security | Struts is an application framework whose secure use depends on safe coding and validation practices. | |
| CIS 4 — Secure Configuration of Enterprise Assets and Software | Struts exposure is amplified when software versions and deployment settings are left ungoverned. | |
| Recommendation — Continuously inventory Struts deployments and remediate known vulnerabilities without delay. Harden Struts applications by reducing unsafe input handling and validating framework-integrated code paths. Standardise secure configuration and version control for all Struts-based deployments. | ||
| OWASP Non-Human Identity Top 10 | NHI-04 — Secrets and Credential Exposure | Struts exploitation often leads to secondary exposure of application secrets and credentials. |
| NHI-07 — Lifecycle and Rotation | Struts risk increases when vulnerable application dependencies remain deployed beyond their safe lifecycle. | |
| NHI-09 — Visibility and Inventory | Managing Struts exposure depends on knowing where the framework is deployed and at what version. | |
| Recommendation — Reduce the blast radius of Struts compromise by protecting secrets reachable from the application tier. Retire vulnerable Struts versions promptly and enforce dependency upgrade lifecycles. Maintain accurate inventory of Struts-backed services and their deployed versions. | ||
| MITRE ATT&CK | T1190 — Exploit Public-Facing Application | Struts vulnerabilities are commonly abused through public-facing web application exploitation. |
| Recommendation — Map hostile requests to public-facing application exploitation and prioritise exposed Struts endpoints for hunting. | ||
Practitioner Guidance
What to watch for: treat Struts as a dependency that requires active inventory and lifecycle ownership, not a “set and forget” library. The highest-risk situations are older internet-facing applications, slow patch cycles, and teams that cannot quickly confirm which Struts version is deployed where.
Practitioner takeaway: if you cannot inventory your Struts deployments and verify patch status quickly, you do not have a reliable control over your exposure.
Related resources from NHI Mgmt Group
- What should teams do first when Apache Struts applications may still use the old file upload mechanism after upgrading?
- What should security teams do first when an Apache Struts file upload flaw can lead to remote code execution?
- What are the signs that an Apache Struts upload exploit is being attempted?
- What happens when a vulnerable Apache Struts server is exploited through the file upload path?
Deepen Your Knowledge
Reviewed and updated by the NHIMG editorial team on September 19, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org
