Yamcs is a mission control framework. Prior to 5.9.4, Yamcs reflects an attacker-controlled redirect_uri parameter from GET /auth/authorize into yamcs-core/src/main/resources/auth/templates/authorize.html without adequate HTML escaping by yamcs-core/src/main/java/org/yamcs/http/auth/AuthHandler.java and yamcs-core/src/main/java/org/yamcs/http/HandlerContext.java. A crafted authorization URL can execute JavaScript when opened by a Yamcs user. The script can access browser-held authentication material and transmit it to an attacker, enabling account compromise. This issue is fixed in version 5.9.4.

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact High

Integrity Impact None

Availability Impact None

User Interaction Required

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
yamcs yamcs affected
Version Status Constraints
< 5.9.4 affected —

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Project Subscriptions

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-rxpg-wjf8-qv9c Yamcs has Reflected XSS in the URL of the Authorize Endpoint
Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/yamcs/yamcs/commit/4d47d5cdcf5d92c2c5bbbc19feada422923332e3 cve-icon cve-icon
https://github.com/yamcs/yamcs/releases/tag/yamcs-5.9.4 cve-icon cve-icon
https://github.com/yamcs/yamcs/security/advisories/GHSA-rxpg-wjf8-qv9c cve-icon cve-icon
History

Fri, 28 Aug 2026 19:45:00 +0000

Type Values Removed Values Added
Description Yamcs is a mission control framework. Prior to 5.9.4, Yamcs reflects an attacker-controlled redirect_uri parameter from GET /auth/authorize into yamcs-core/src/main/resources/auth/templates/authorize.html without adequate HTML escaping by yamcs-core/src/main/java/org/yamcs/http/auth/AuthHandler.java and yamcs-core/src/main/java/org/yamcs/http/HandlerContext.java. A crafted authorization URL can execute JavaScript when opened by a Yamcs user. The script can access browser-held authentication material and transmit it to an attacker, enabling account compromise. This issue is fixed in version 5.9.4.
Title Yamcs: Reflected XSS in the URL of the Authorize Endpoint
Weaknesses CWE-79
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-08-28T17:15:52.840Z

Reserved: 2026-06-16T23:01:04.075Z

Link: CVE-2026-55549

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-08-28T20:18:28.657

Modified: 2026-08-28T20:18:28.657

Link: CVE-2026-55549

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-28T21:30:05Z

Weaknesses