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

{
  "id": "db5e8d449bec3634db5177b66a56fdfd531f9f1bc80a19a18e7644af19661db5",
  "url": "https://osv.dev/vulnerability/CVE-2026-42177",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "linux-entra-sso: PRT SSO cookie can leak to attacker-controlled hosts when broad host permissions are granted",
    "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.",
    "evidence": "osv:CVE-2026-42177",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-42177",
      "aliases": [
        "CVE-2026-42177",
        "GHSA-52rj-42vh-2rxc"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/siemens/linux-entra-sso",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "88fb9104ebf584b30c8a0a032f85b9604465d251"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.8.1"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.8.1"
                      }
                    ],
                    "source": "DESCRIPTION"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v1.8.0",
            "v1.7.2",
            "v1.7.1",
            "v1.7.0",
            "v1.6.0",
            "v1.5.1",
            "v1.5.0",
            "v1.4.0",
            "v1.3.1",
            "v1.3.0",
            "v1.2.0",
            "v1.1.0",
            "v1.0",
            "v0.9",
            "v0.8",
            "v0.7",
            "v0.6.1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-42177.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:50.194235653Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42177.json",
        "https://github.com/siemens/linux-entra-sso/security/advisories/GHSA-52rj-42vh-2rxc",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-42177"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-284",
          "CWE-436"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42177.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-42177",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 518888,
  "published_at": "2026-05-12T17:11:36.05+00:00"
}