Vulnerability in linux-entra-sso (CVE-2026-42177)
Summary
Vulnerability in linux-entra-sso (CVE-2026-42177). Confidential information can be exposed externally. Mitigation: upgrade to 1.8.1 or later.
Original description
The description as published by the source.
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: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-42177 has been found in linux-entra-sso.
Confidential information can be exposed externally. CVSS score: 5.3/10.
What to do: upgrade linux-entra-sso to 1.8.1 or later.
If unsure, ask your IT team or search "linux-entra-sso CVE-2026-42177" on the vendor's site.
CVE-2026-42177 (linux-entra-sso) — CWE-284 / CVSS v3 5.3
Attack vector: remote (network-reachable) / unauthenticated
Patched: 1.8.1 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-284) exists in linux-entra-sso.
Check the vendor advisory for the affected versions of linux-entra-sso.
Severity: Medium (CVSS 5.3/10). Confidential information can be exposed externally.
Update to 1.8.1.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'linux-entra-sso' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'linux-entra-sso' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
linux-entra-ssoを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade linux-entra-sso to 1.8.1ステージング環境で 1.8.1 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
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3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-42177 linux-entra-sso Fixed in: 1.8.1-1
- Ubuntu UBUNTU-CVE-2026-42177 linux-entra-sso
References
- advisory github.com
- advisory github.com
- advisory nvd.nist.gov