Atomicorp WAF Research Note: CVE-2021-21234

Spring Boot Actuator Logview Directory Traversal

Research Notes

This page documents research related to exploit techniques, attack behaviors, testing results, and WAF rule interactions associated with this vulnerability.

Research finding: this note documents observed WAF protections relevant to exploit techniques associated with this vulnerability.

These notes are not intended to represent the full set of vulnerabilities mitigated by Atomicorp products and should not be interpreted as a coverage matrix, certification list, or census of protected CVEs.

Atomicorp WAF protections are primarily designed around attack techniques and exploit behaviors rather than individual vulnerability identifiers. A published research note documents a positive research finding related to that CVE. If a CVE is absent from these notes, no conclusion should be drawn about protection status.

Vulnerability Description

spring-boot-actuator-logview in a library that adds a simple logfile viewer as spring boot actuator endpoint. It is maven package “eu.hinsch:spring-boot-actuator-logview”. In spring-boot-actuator-logview before version 0.2.13 there is a directory traversal vulnerability. The nature of this library is to expose a log file directory via admin (spring boot actuator) HTTP endpoints. Both the filename to view and a base folder (relative to the logging folder root) can be specified via request parameters. While the filename parameter was checked to prevent directory traversal exploits (so that filename=../somefile would not work), the base folder parameter was not sufficiently checked, so that filename=somefile&base=../ could access a file outside the logging base directory). The vulnerability has been patched in release 0.2.13. Any users of 0.2.12 should be able to update without any issues as there are no other changes in that release. There is no workaround to fix the vulnerability other than updating or removing the dependency. However, removing read access of the user the application is run with to any directory not required for running the application can limit the impact. Additionally, access to the logview endpoint can be limited by deploying the application behind a reverse proxy.

Public Vulnerability References

• NVD
• CVE Record

CVE Details

• CVE: CVE-2021-21234
• Name: Spring Boot Actuator Logview Directory Traversal
• Severity: high
• CVSS: 7.7 (High)
• CVSS source: N/A
• Vendor: spring-boot-actuator-logview_project
• Product: spring-boot-actuator-logview
• Latest protected observation: 2026-07-03
• Rule IDs observed: 340007, 347009

Test or Research Source

• Source: http/cves/2021/CVE-2021-21234.yaml
• Tags: actuator, cve, cve2021, lfi, spring-boot-actuator-logview_project, springboot, vkev, vuln

Research Note Context

This research note documents exploit-technique analysis associated with this vulnerability and references Atomicorp WAF protections observed during engineering review, testing, or validation activities.

Atomicorp security controls are generally designed to identify and mitigate attack techniques and exploit behaviors rather than individual CVE identifiers. As a result, protections developed for one vulnerability may also apply to related attack variants and future vulnerabilities using similar techniques.

Learn More

Atomicorp develops commercially supported security technologies for web applications, servers, endpoints, workloads, and legacy enterprise platforms.

Organizations interested in protecting systems against exploit techniques associated with vulnerabilities such as this one can learn more about:

• Atomic ModSecurity Rules: commercially maintained WAF rules for ModSecurity deployments, including protections for web attacks, bots, scanners, malware, exploitation attempts, and emerging vulnerability classes.
• Atomic WAF: an enterprise web application firewall with Atomicorp rules, centralized management, reporting, authentication controls, and operational tooling.
• Atomic ModSecurity Integrator: a special licensing option for MSPs, MSSPs, OEMs, VARs, reverse proxy providers, and other integrators who want to incorporate Atomicorp ModSecurity rule technology into their own products or services.
• Atomic OSSEC: an enterprise OSSEC-based intrusion detection, compliance, and security monitoring platform.
• Atomic Protector: workload protection for Linux, web, cloud, data center, and hybrid environments.

For additional information, product evaluations, or technical discussions, visit https://www.atomicorp.com/ or https://modsecurity.io/ .