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TI-2026-30502 Aliases CVE-2026-42177

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

Priority MEDIUM 57CWE-284Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Required
Attack complexity
High
Impact type
Security bypass
Confidentiality · integrity · availability
High · None · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-284.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00234 14th percentileScored 2026-11-07
Fix Fixed linux-entra-sso (siemens): 1.8.1

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
Siemenslinux-entra-ssobefore 1.8.11.8.1Patch availableCNA
  • linux-entra-sso VendorSiemens Affected before 1.8.1 Fixed in 1.8.1 Patch available CNA

Remediation

  • Fix · CNA linux-entra-sso (siemens) Fixed in 1.8.1

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-42177

References

Other 1

  • TI-2026-20057 Authentication bypass in Fortinet FortiWeb KEVCVSS 3.1CRITICAL 9.4
  • TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
  • TI-2025-18911 Heap-based buffer overflow in Fortinet FortiSwitchManager KEVCVSS 3.1CRITICAL 9.8
  • TI-2025-09686 Type confusion in Google Chrome KEVCVSS 3.1CRITICAL 9.8
  • TI-2022-07142 Code injection in Spring Framework KEVCVSS 3.1CRITICAL 9.8
  • TI-2021-19919 Apache Log4j2 JNDI features do not protect against attacker controlled LDAP and other JNDI related endpoints KEVCVSS 3.1CRITICAL 10.0
See all 2487 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences