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

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Summary

CVECVE-2026-42177
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-12 18:17:24 UTC
Updated2026-05-12 18:17:24 UTC
Descriptionlinux-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.

Risk And Classification

Primary CVSS: v3.1 5.3 MEDIUM from [email protected]

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

Problem Types: CWE-284 | CWE-436 | CWE-284 CWE-284: Improper Access Control | CWE-436 CWE-436: Interpretation Conflict

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.3MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
3.1CNADECLARED5.3MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N

CVSS v3.1 Breakdown

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

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Siemens Linux-entra-sso affected < 1.8.1 Not specified

References

ReferenceSourceLinkTags
github.com/siemens/linux-entra-sso/security/advisories/GHSA-52rj-42vh-2rxc [email protected] github.com
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