Yamcs: Unauthenticated Directory Traversal
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Information disclosure
- Confidentiality · integrity · availability
- High · None · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-22 and the CVSS impact.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| yamcs | yamcs | before 5.12.0 | 5.12.0 | Patch available | CNA |
| — | org.yamcs:yamcs-core (Maven) | before 5.12.0 | 5.12.0 | Patch available | GHSA-9jg3-g3wh-w9pj |
- yamcs Vendoryamcs Affected before 5.12.0 Fixed in 5.12.0 Patch available CNA
- org.yamcs:yamcs-core (Maven) Vendor— Affected before 5.12.0 Fixed in 5.12.0 Patch available GHSA-9jg3-g3wh-w9pj
Remediation
- Fix · CNA yamcs (yamcs) Fixed in 5.12.0
- Fix · GHSA-9jg3-g3wh-w9pj org.yamcs:yamcs-core (Maven) Fixed in 5.12.0 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-55552
- 2026-10-03 Alias added: GHSA-9jg3-g3wh-w9pj
- 2026-10-06 EPSS moved to the 50th–90th percentile
References
Other 6
- 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/yamcs/yamcs
More yamcs vulnerabilities
- TI-2026-40103 Yamcs: Remote Code Execution via instance-template argument YAML injection (createInstance) CVSS 3.1CRITICAL 9.8
- TI-2026-34240 Yamcs: Remote Code Execution via Mission Database algorithm override CVSS 3.1CRITICAL 9.8
- TI-2026-32507 Yamcs: No Rate Limiting on Authentication Endpoint CVSS 3.1CRITICAL 9.8
- TI-2026-40106 Yamcs: Authenticated remote code execution via unescaped StreamSQL `LIKE` pattern compiled by Janino (`LikeExpression`) CVSS 3.1CRITICAL 9.9
- TI-2026-40057 Yamcs: Authenticated RCE via StreamSQL aggregate-compiler column-name injection in Yamcs `executeSql` CVSS 3.1CRITICAL 9.1
- TI-2026-34277 Yamcs: Authenticated Remote Code Execution (RCE) via Jython Algorithm Code Injection CVSS 3.1CRITICAL 9.1
Sources
- CVE-2026-55552 · CVE Program
- CVE-2026-55552 · NVD
- FIRST EPSS
- GHSA-9jg3-g3wh-w9pj · GitHub Advisory Database · CC BY 4.0
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