Yamcs: WebSocket subscription handlers omit the privilege checks their REST siblings enforce
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Security bypass
- 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-862.
Summary
Yamcs is a mission control framework. Prior to 5.12.8 and 5.13.2, Yamcs WebSocket subscription handlers fail to enforce the privileges required by equivalent REST endpoints. PacketsApi.subscribePackets exposes the packets WebSocket topic without ObjectPrivilegeType.ReadPacket, ProcessingApi.subscribeAlgorithmStatus exposes the algorithm-status WebSocket topic without ObjectPrivilegeType.ReadAlgorithm, and MdbOverrideApi.subscribeMdbChanges exposes the mdb-changes WebSocket topic without SystemPrivilege.GetMissionDatabase. A low-privilege authenticated user can receive telemetry packets, algorithm status, and mission database change information outside the assigned authorization scope. This issue is fixed in versions 5.12.8 and 5.13.2.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- 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 5.12.8; 5.13.0 to before 5.13.2 | 5.12.8, 5.13.2 | Patch available | CNA |
| — | org.yamcs:yamcs-core (Maven) | before 5.12.8 | 5.12.8 | Patch available | GHSA-fwww-cp23-7f5g |
| — | org.yamcs:yamcs-core (Maven) | 5.13.0 to before 5.13.2 | 5.13.2 | Patch available | GHSA-fwww-cp23-7f5g |
- yamcs Vendoryamcs Affected before 5.12.8; 5.13.0 to before 5.13.2 Fixed in 5.12.8, 5.13.2 Patch available CNA
- org.yamcs:yamcs-core (Maven) Vendor— Affected before 5.12.8 Fixed in 5.12.8 Patch available GHSA-fwww-cp23-7f5g
- org.yamcs:yamcs-core (Maven) Vendor— Affected 5.13.0 to before 5.13.2 Fixed in 5.13.2 Patch available GHSA-fwww-cp23-7f5g
Remediation
- Fix · CNA yamcs (yamcs) Fixed in 5.12.8, 5.13.2
- Fix · GHSA-fwww-cp23-7f5g org.yamcs:yamcs-core (Maven) Fixed in 5.12.8 Advisory →
- Fix · GHSA-fwww-cp23-7f5g org.yamcs:yamcs-core (Maven) Fixed in 5.13.2 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-55545
- 2026-10-03 Alias added: GHSA-fwww-cp23-7f5g
References
Other 6
- https://github.com/yamcs/yamcs/security/advisories/GHSA-fwww-cp23-7f5g
- https://github.com/yamcs/yamcs/commit/0691731846c5a0aca81b88fabbd2cd51d56fe076
- https://github.com/yamcs/yamcs/commit/12864af555e6ca4941b01c1f1217859cc0492ce0
- https://github.com/yamcs/yamcs/releases/tag/yamcs-5.12.8
- https://github.com/yamcs/yamcs/releases/tag/yamcs-5.13.2
- 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-2026-55545 · CVE Program
- CVE-2026-55545 · NVD
- FIRST EPSS
- GHSA-fwww-cp23-7f5g · GitHub Advisory Database · CC BY 4.0
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