fix: relax CSP for non-Teams SSO pages to unblock eval-dependent login

[IsmaelMartinez]

Summary

Fixes login failure for users with third-party SSO providers (e.g. Symantec VIP) that use Angular/jQuery requiring eval().

Strips all CSP headers (Content-Security-Policy and Content-Security-Policy-Report-Only) from non-Teams domain responses, so third-party SSO pages aren't blocked by their own restrictive CSP when running with contextIsolation: false. Teams domains (including MCAS proxy suffix) are explicitly excluded from any CSP modification.

Root cause

The Symantec VIP login page delivers CSP via both HTTP headers and potentially <meta> tags. With contextIsolation: false (our architectural choice for DOM access), the shared V8 context enforces even the Content-Security-Policy-Report-Only policy as a blocking policy, causing Uncaught EvalError in the VIP userservices script and preventing the Angular-based login UI from initializing.

The initial fix (adding 'unsafe-eval' to script-src) didn't work because the CSP is likely delivered via <meta> tags in the HTML, which HTTP header modification can't reach. Stripping all CSP headers handles the HTTP header case. A separate PR will add a contextIsolation config option as a guaranteed fallback.

Test plan

• Verify normal Teams login flow still works (no CSP changes for Teams domains)
• Verify Symantec VIP SSO login completes successfully
• Verify other third-party SSO providers are not broken
• Run npm run lint — passes clean

Closes #2326

🤖 Generated with Claude Code

[github-actions]

✅ Changelog entry generated and committed to this PR:

Fix: Relax CSP for non-Teams SSO to unblock eval-dependent login - by @IsmaelMartinez (#2330)

The file .changelog/pr-2330.txt will be included when you merge this PR.

You can edit it directly in this PR if needed.

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a critical login issue for users of third-party Single Sign-On (SSO) providers by selectively relaxing the Content Security Policy (CSP). The change specifically targets non-Teams domains to permit the use of eval() in scripts, which is required by some SSO UIs, without compromising the security policies enforced on core Teams domains. This ensures broader compatibility for authentication while maintaining security where it's most critical.

Highlights

• SSO Login Fix: Resolved login failures for users utilizing third-party SSO providers (e.g., Symantec VIP) that depend on eval() for their Angular/jQuery-based UIs.
• Content Security Policy (CSP) Relaxation: Introduced 'unsafe-eval' to the script-src directive of the CSP for non-Teams domains only, allowing dynamic code evaluation necessary for certain SSO flows.
• Teams Domain Preservation: Ensured that the original CSP for Teams domains, including those with Microsoft Cloud App Security (MCAS) proxy suffixes, remains entirely unchanged to maintain existing security postures.
• Domain Identification Logic: Implemented a utility function to accurately identify Teams domains, accounting for potential MCAS proxy suffixes, to selectively apply CSP modifications.

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Changelog

• app/mainAppWindow/index.js
  • Added TEAMS_DOMAINS constant to list known Teams domains.
  • Implemented isTeamsDomain function to check if a given URL belongs to a Teams domain, including handling MCAS proxy suffixes.
  • Introduced relaxCspForAuthPages function to modify the Content-Security-Policy header by adding 'unsafe-eval' to script-src for non-Teams domains.
  • Integrated relaxCspForAuthPages into the onHeadersReceivedHandler to apply the CSP relaxation during header processing.

Activity

• No activity has been recorded for this pull request yet.

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[gemini-code-assist]

Code Review

This pull request relaxes the Content Security Policy for non-Teams domains by adding 'unsafe-eval' to the script-src directive. This is a deliberate change to support third-party SSO providers that rely on eval(). The implementation correctly restricts this change to non-Teams domains, leaving the CSP for Teams pages untouched. I have one suggestion to improve the robustness of how the CSP string is modified, ensuring that only the script-src directive is affected.

[github-actions]

📦 PR Build Artifacts

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🐧 Linux

x86_64 (434.03 MB) - Contains: .deb, .rpm, .tar.gz, .AppImage

• teams-for-linux-linux-x64

arm64 (425.25 MB) - Contains: .deb, .rpm, .tar.gz, .AppImage

• teams-for-linux-linux-arm64

armv7l (403.29 MB) - Contains: .deb, .rpm, .tar.gz, .AppImage

• teams-for-linux-linux-armv7l

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x86_64 (124.84 MB) - Contains: .dmg

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🕐 Last updated: 2026-03-13 07:26 UTC

[github-actions]

📦 PR Snap Build Artifacts

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🐧 Linux Snap Packages

x86_64 (107.27 MB)

• teams-for-linux-snap-x64

arm64 (104.18 MB)

• teams-for-linux-snap-arm64

armv7l (98.41 MB)

• teams-for-linux-snap-armv7l

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud