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CVE-2026-55559— Yamcs: Remote Code Execution via instance-template argument YAML injection (createInstance)

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（Mission Control）框架。在 5.12.8 和 5.13.2 之前，Yamcs 会将来自 POST /api/instances 和 PATCH /api/instances/{instance} 的 通过 （位于 ）插入到 YAML 中，且未进行 YAML 上下文转义。渲染后的配置由 解析，并由 加载，这使得攻击者能够注入一个针对 的服务条目。在未配置 的部署环境中，该操作可通过 guest 超级用户执行；而在已启用安全机制的部署环境中，则需要具备 权限。成功利用此漏洞后，

CVSS 9.8 · Critical

Affected Version Matrix 2

VendorProduct Version RangeStatus
yamcs yamcs < 5.12.8 affected
>= 5.13.0, < 5.13.2 affected
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I. Basic Information for CVE-2026-55559

Vulnerability Information
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Vulnerability Title
Yamcs: Remote Code Execution via instance-template argument YAML injection (createInstance)
Source: CVE Program / CVE List V5
Vulnerability Description
Yamcs is a mission control framework. Prior to 5.12.8 and 5.13.2, Yamcs inserts templateArgs from POST /api/instances and PATCH /api/instances/{instance} into YAML through VarStatement.append in yamcs-core/src/main/java/org/yamcs/templating/VarStatement.java without YAML-context escaping. The rendered configuration is parsed by YamcsServer.createInstance and loaded by YamcsServerInstance, allowing an attacker to inject a services entry for org.yamcs.ProcessRunner. Deployments without security.yaml expose the operation through the guest superuser, while secured deployments require SystemPrivilege.CreateInstances. Successful exploitation executes commands as the Yamcs service account. This issue is fixed in versions 5.12.8 and 5.13.2.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
对生成代码的控制不恰当(代码注入)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
yamcs yamcs < 5.12.8 -

II. Public POCs for CVE-2026-55559

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III. Intelligence Information for CVE-2026-55559

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Patches & Fixes for CVE-2026-55559 (2)

Vendor Advisories for CVE-2026-55559 (1)

Vendor Pages for CVE-2026-55559 (2)

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-2026-55511 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-2026-55549 6.5 MEDIUM Yamcs: Reflected XSS in the URL of the Authorize Endpoint
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-94

V. Comments for CVE-2026-55559

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