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CVE-2026-42177— linux-entra-sso: PRT SSO cookie can leak to attacker-controlled hosts when broad host permissions are granted

Quick assessment

Affected
siemens linux-entra-sso
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.

Entra ID SSO via Microsoft Identity Broker on Linux是Siemens开源的一款Linux设备上通过微软身份代理实现单点登录的浏览器扩展。 Entra ID SSO via Microsoft Identity Broker on Linux 1.8.1之前版本存在访问控制错误漏洞，该漏洞源于Chrome适配器未正确检查URL前缀，可能导致主框架导航时附加PRT Cookie到攻击者控制的主机。

CVSS 5.3 · Medium EPSS 0.31% · P21

Possible ATT&CK Techniques 1 AI

T1556.004 · Network Device Authentication

Affected Version Matrix 1

VendorProduct Version RangeStatus
siemens linux-entra-sso < 1.8.1 affected
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I. Basic Information for CVE-2026-42177

Vulnerability Information
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Vulnerability Title
linux-entra-sso: PRT SSO cookie can leak to attacker-controlled hosts when broad host permissions are granted
Source: CVE Program / CVE List V5
Vulnerability Description
linux-entra-sso is a browser plugin for Linux to SSO on Microsoft Entra ID. Prior to 1.8.1, platform/chrome/js/platform-chrome.js:69-88 registers a single declarativeNetRequest rule whose urlFilter is Platform.SSO_URL + "/*", i.e. "https://login.microsoftonline.com/*". Chrome's urlFilter without a | or || anchor is substring-matched against the full request URL. The same applied rule action is modifyHeaders that attaches the Entra ID Primary Refresh Token cookie. The Firefox adapter in platform/firefox/js/platform-firefox.js:53 performs a belt-and-braces startsWith(Platform.SSO_URL) check before injecting the header; the Chrome adapter does not. When the extension holds broad host permissions through the optional_host_permissions: ["https://*/*"] declared in platform/chrome/manifest.json:34, a main-frame navigation to a URL whose path embeds https://login.microsoftonline.com/ causes Chrome to attach the PRT cookie to the request to the attacker-controlled host. This vulnerability is fixed in 1.8.1.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
访问控制不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
Entra ID SSO via Microsoft Identity Broker on Linux 访问控制错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Entra ID SSO via Microsoft Identity Broker on Linux是Siemens开源的一款Linux设备上通过微软身份代理实现单点登录的浏览器扩展。 Entra ID SSO via Microsoft Identity Broker on Linux 1.8.1之前版本存在访问控制错误漏洞，该漏洞源于Chrome适配器未正确检查URL前缀，可能导致主框架导航时附加PRT Cookie到攻击者控制的主机。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
siemens linux-entra-sso < 1.8.1 -

II. Public POCs for CVE-2026-42177

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III. Intelligence Information for CVE-2026-42177

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Vendor Advisories for CVE-2026-42177 (1)

Same Patch Batch · siemens · 2026-05-12 · 20 CVEs total

CVE-2026-41551 9.1 CRITICAL Siemens ROS# 安全漏洞
CVE-2025-40949 9.1 CRITICAL Siemens多款产品 操作系统命令注入漏洞
CVE-2026-22924 9.1 CRITICAL Siemens SIMATIC CN 4100 访问控制错误漏洞
CVE-2026-25787 9.1 CRITICAL Siemens SIMATIC 跨站脚本漏洞
CVE-2026-25786 9.1 CRITICAL Siemens多款产品 跨站脚本漏洞
CVE-2025-40946 8.3 HIGH Siemens多款产品 安全漏洞
CVE-2025-12659 7.8 HIGH Heap-based buffer overflow in Siemens Simcenter Femap
CVE-2026-44412 7.8 HIGH Siemens Solid Edge 安全漏洞
CVE-2026-44411 7.8 HIGH Siemens Solid Edge 缓冲区错误漏洞
CVE-2026-27662 7.7 HIGH Siemens SIMATIC HMI Comfort Panels 安全漏洞
CVE-2026-22925 7.5 HIGH Siemens SIMATIC CN 4100 安全漏洞
CVE-2026-33893 7.5 HIGH Siemens多款产品 信任管理问题漏洞
CVE-2025-40947 7.5 HIGH Siemens RUGGEDCOM 操作系统命令注入漏洞
CVE-2025-40833 7.5 HIGH Siemens多款产品 代码问题漏洞
CVE-2026-33862 7.3 HIGH Siemens Teamcenter 跨站脚本漏洞
CVE-2026-25789 7.1 HIGH Siemens多款产品 跨站脚本漏洞
CVE-2025-40948 6.8 MEDIUM Siemens多款产品 参数注入漏洞
CVE-2026-41125 6.0 MEDIUM Siemens多款产品 SQL注入漏洞
CVE-2024-54017 5.3 MEDIUM Siemens SIPROTEC 5 安全漏洞

IV. Related Vulnerabilities

Same vendor: siemens
Same weakness: CWE-284

V. Comments for CVE-2026-42177

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