CVE-2026-55521

Received Received - Intake

Unauthorized Access in Yamcs Mission Control Framework

Publication date: 2026-08-28

Last updated on: 2026-08-28

Assigner: GitHub, Inc.

Description

Yamcs is a mission control framework. Prior to 5.12.8 and 5.13.2, Yamcs omits authorization checks in IndexesApi.listPacketIndex, IndexesApi.listEventIndex, Cop1Api.disable, Cop1Api.resume, Cop1Api.initialize, Cop1Api.updateConfig, and TimeApi.setTime. An authenticated low-privilege user can read packet and event index metadata without ObjectPrivilegeType.ReadPacket, alter COP-1 link state without SystemPrivilege.ControlLinks, and manipulate simulation time. These operations can disclose telemetry metadata, disrupt telecommand handling, and affect system integrity and availability. This issue is fixed in versions 5.12.8 and 5.13.2.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-08-28

Last Modified

2026-08-28

Generated

2026-08-29

AI Q&A

2026-08-29

EPSS Evaluated

N/A

NVD

CVE-2026-55521

EUVD

EUVD-2026-67838

Affected Vendors & Products

Vendor	Product	Version / Range
yamcs	yamcs	to 5.12.8\|end_excluding=5.13.2 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-862	The product does not perform an authorization check when an actor attempts to access a resource or perform an action.

Attack-Flow Graph

Executive Summary

CVE-2026-55521 is a security vulnerability in Yamcs, a mission control framework. It involves missing authorization checks in several API components (IndexesApi, Cop1Api, TimeApi). An authenticated low-privilege user can exploit these flaws to read sensitive telemetry metadata, disrupt satellite communication protocols (COP-1), and manipulate simulation time without proper privileges.

Detection Guidance

Detecting this vulnerability requires checking if your Yamcs instance is running a vulnerable version (up to 5.13.1 or 5.12.7) and verifying if unauthorized privilege checks are missing. Inspect the Yamcs logs for API calls to IndexesApi, Cop1Api, or TimeApi without proper authorization. Check for unusual activity in packet/event index access, COP-1 link state changes, or simulation time modifications by low-privilege users.

Impact Analysis

This vulnerability allows unauthorized users to access sensitive data like packet and event indexes, disrupt critical satellite communication links, and alter system time settings. This could lead to data breaches, system downtime, or incorrect mission operations due to compromised integrity and availability.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating GDPR's data protection principles and HIPAA's security requirements for protected health information. Non-compliance risks include legal penalties, reputational damage, and loss of trust due to compromised confidentiality and integrity of sensitive data.

Mitigation Strategies

Upgrade Yamcs to version 5.12.8 or 5.13.2 or later immediately. Review and enforce privilege checks for all API endpoints, particularly IndexesApi, Cop1Api, and TimeApi. Restrict access to sensitive operations and audit user permissions to ensure only authorized users can perform privileged actions.

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