Siemens linux-entra-sso up to 1.8.0 on Linux Refresh Token platform-chrome.js access control

Summaryinfo

A vulnerability described as critical has been identified in Siemens linux-entra-sso up to 1.8.0 on Linux. The affected element is an unknown function of the file platform/chrome/js/platform-chrome.js of the component Refresh Token Handler. The manipulation results in access control. This vulnerability is known as CVE-2026-42177. It is possible to launch the attack remotely. No exploit is available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability, which was classified as problematic, was found in Siemens linux-entra-sso up to 1.8.0 on Linux. Affected is an unknown code block of the file platform/chrome/js/platform-chrome.js of the component Refresh Token Handler. The manipulation with an unknown input leads to a access control vulnerability. CWE is classifying the issue as CWE-284. The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. This is going to have an impact on confidentiality. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability is traded as CVE-2026-42177 since 04/25/2026. The exploitability is told to be difficult. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 05/12/2026). This vulnerability is assigned to T1068 by the MITRE ATT&CK project.

Upgrading to version 1.8.1 eliminates this vulnerability.

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Productinfo

Vendor

• Siemens

Name

• linux-entra-sso

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4
• 1.5
• 1.6
• 1.7
• 1.8.0

License

• commercial

Website

• Vendor: https://www.siemens.com/
• Product: https://github.com/siemens/linux-entra-sso/

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