Yamcs: Reflected XSS in the URL of the Authorize Endpoint

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-55549
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-28 20:18:28 UTC
Updated2026-09-01 02:16:58 UTC
DescriptionYamcs 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.

Risk And Classification

Primary CVSS: v3.1 6.5 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

EPSS: 0.003610000 probability, percentile 0.290300000 (date 2026-08-31)

Problem Types: CWE-79 | CWE-79 CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
3.1CNADECLARED6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Yamcs Yamcs affected < 5.9.4 Not specified

References

ReferenceSourceLinkTags
github.com/yamcs/yamcs/security/advisories/GHSA-rxpg-wjf8-qv9c 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
github.com/yamcs/yamcs/commit/4d47d5cdcf5d92c2c5bbbc19feada422923332e3 [email protected] github.com
github.com/yamcs/yamcs/releases/tag/yamcs-5.9.4 [email protected] github.com
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