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CVE-2026-55549— Yamcs: Reflected XSS in the URL of the Authorize Endpoint

Quick assessment

Affected
yamcs yamcs
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Yamcs 是一个任务控制框架。在 5.9.4 版本之前，Yamcs 的 端点会将攻击者可控的 参数直接反射到 模板中，且未通过 和 进行充分的 HTML 转义。攻击者可以构造一个特殊的授权 URL，当 Yamcs 用户打开该 URL 时，其中嵌入的 JavaScript 代码将被执行。该脚本能够访问浏览器中存储的认证信息，并将其传输给攻击者，从而导致账户被盗。此问题已在 5.9.4 版本中修复。

CVSS 6.5 · Medium

Possible ATT&CK Techniques 1 AI

T1189 · Drive-by Compromise

Affected Version Matrix 1

VendorProduct Version RangeStatus
yamcs yamcs < 5.9.4 affected
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I. Basic Information for CVE-2026-55549

Vulnerability Information
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Vulnerability Title
Yamcs: Reflected XSS in the URL of the Authorize Endpoint
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
在Web页面生成时对输入的转义处理不恰当(跨站脚本)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
yamcs yamcs < 5.9.4 -

II. Public POCs for CVE-2026-55549

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III. Intelligence Information for CVE-2026-55549

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Patches & Fixes for CVE-2026-55549 (1)

Vendor Advisories for CVE-2026-55549 (1)

Same Patch Batch · yamcs · 2026-08-28 · 9 CVEs total

CVE-2026-55565 9.9 CRITICAL Yamcs: Authenticated remote code execution via unescaped StreamSQL `LIKE` pattern compiled
CVE-2026-55559 9.8 CRITICAL Yamcs: Remote Code Execution via instance-template argument YAML injection (createInstance
CVE-2026-55511 9.1 CRITICAL Yamcs: Authenticated RCE via StreamSQL aggregate-compiler column-name injection in Yamcs `
CVE-2026-55521 8.8 HIGH Yamcs : Multiple Missing Function Level Access Control vulnerabilities in Yamcs Core API
CVE-2026-55552 7.5 HIGH Yamcs: Unauthenticated Directory Traversal
CVE-2026-55545 6.5 MEDIUM Yamcs: WebSocket subscription handlers omit the privilege checks their REST siblings enfor
CVE-2026-55547 4.3 MEDIUM Yamcs: Missing Authorization on Role and Privilege Enumeration Endpoints Allows Any Authen
CVE-2026-55566 4.3 MEDIUM Yamcs: DOM XSS in Extension Routing

IV. Related Vulnerabilities

Same product: yamcs
Same vendor: yamcs
Same weakness: CWE-79

V. Comments for CVE-2026-55549

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