🛡️ Sentinel: [HIGH] 인라인 스타일 'unsafe-inline' CSP 보안 취약점 수정 및 Nonce 기반 정책 적용

[seonghobae]

🚨 보안 심각도 (Security Severity): HIGH

정적 웹 생성기에서 생성된 HTML 결과물은 파일 경로나 이름 등에서 입력되는 예상치 못한 악의적인 페이로드에 노출될 수 있습니다. 기존 버전에서는 style-src 'unsafe-inline' CSP 지시어가 허용되어 인라인 CSS 인젝션을 통한 잠재적 XSS(Cross-Site Scripting) 우회 공격이 가능했습니다.

💡 취약점 (Vulnerability)

html4tree의 생성된 index.html 파일 내부에는 디자인 렌더링을 위해 CSS 인라인 스타일 블록(<style>)이 포함되어 있으며, style="display:block; width:100%" 등의 인라인 스타일 속성이 HTML 태그에 직접 지정되어 있었습니다. 이 때문에 기존의 Content-Security-Policy 메타 태그가 'unsafe-inline'을 강제로 허용하고 있었습니다.

🎯 임팩트 (Impact)

만약 어떤 경로를 통해 악성 사용자가 이 도구의 입력(예: 악의적인 파일 및 폴더 이름 생성 등)을 변조할 수 있다면, 인라인 스타일 허용 정책(unsafe-inline)을 이용해 악성 CSS 또는 우회된 자바스크립트를 로드하도록 조작할 위험이 존재합니다.

🔧 해결 방안 (Fix)

본 수정 사항에서는 Nonce 기반의 CSP를 도입하여 방어 심층(Defense in Depth) 보안을 강화했습니다.

1. java.security.SecureRandom을 활용하여 디렉토리가 처리될 때마다 16바이트 길이의 동적인 랜덤 Nonce 값을 생성하고, Base64로 인코딩합니다.
2. <style> 태그에 nonce="${nonce}" 속성을 추가하여 해당 스타일 블록이 안전함을 선언합니다.
3. 기존 HTML 요소 내부의 인라인 style 속성들을 제거하고 .dir-link, .empty-dir 같은 CSS 클래스로 대체하여 인라인 스타일 사용을 원천 차단했습니다.
4. Content-Security-Policy 메타 태그의 설정을 변경하여 'unsafe-inline'을 제거하고, 동적으로 생성된 'nonce-...' 값만을 허용하도록 수정했습니다.

✅ 검증 완료 (Verification)

• Jacoco를 이용한 테스트 커버리지가 **100%**를 유지하는지 검증 완료되었습니다. (MainTest.kt 테스트 코드 내 CSP 기대 문자열 변경 완료)
• Playwright를 사용해 변경 후 생성된 HTML UI가 시각적으로 깨지지 않고 정상 렌더링 됨을 스크린샷과 비디오를 통해 검증하였습니다.
• Sentinel 보안 저널(.jules/sentinel.md)에 해당 사항이 기록되었습니다.

---

PR created automatically by Jules for task 17083573628632093851 started by @seonghobae

[google-labs-jules]

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---

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[opencode-agent]

OpenCode Review Overview

• Head SHA: ae1e1c98d3663af6105bd1038e44fd66d60cd0e6
• Workflow run: 29151400012
• Workflow attempt: 1
• Gate result: REQUEST_CHANGES (approval step)

Pull request overview

OpenCode reviewed the current-head mergeability evidence and changed-file flow before approval, then found merge conflicts on the affected path.

Findings

1. HIGH Merge Conflict Guidance - Resolve the PR branch against the latest base branch

• Problem: GitHub reports mergeStateStatus DIRTY for this pull request.
• Root cause: Branch sentinel/csp-nonce-enhancement-17083573628632093851 cannot be merged cleanly into master; the changed-file flow below shows which review/runtime path is blocked by the conflict.
• Fix: Merge or rebase the latest master into sentinel/csp-nonce-enhancement-17083573628632093851, resolve conflict markers in the PR branch, rerun the focused checks, and push the same branch.
• Repair commands:

gh pr checkout 127 --repo ContextualWisdomLab/html4tree
git fetch origin master
git merge --no-ff origin/master  # or: git rebase origin/master
git status --short
# resolve files, then git add <resolved-files>
# merge path: git commit
# rebase path: git rebase --continue
git push origin HEAD:sentinel/csp-nonce-enhancement-17083573628632093851
# rebase path only: git push --force-with-lease origin HEAD:sentinel/csp-nonce-enhancement-17083573628632093851

• Regression test: Keep OpenCode approval gated on mergeability so model-output failures cannot approve a conflicted PR.

Merge Conflict Evidence Map

flowchart LR
  PR["PR changed files"] --> Evidence["OpenCode bounded evidence"]
  Evidence --> S1["Changed file (3 files)"]
  S1 --> I1["repository behavior"]
  I1 --> Conflict["Merge conflict blocks this path"]
  Conflict --> V1["required checks"]

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• Result: REQUEST_CHANGES
• Reason: mergeStateStatus is DIRTY; mergeable is CONFLICTING.
• Head SHA: ae1e1c98d3663af6105bd1038e44fd66d60cd0e6
• Workflow run: 29151400012
• Workflow attempt: 1

Changed-File Evidence Map

flowchart LR
  PR["PR changed files"] --> Evidence["OpenCode bounded evidence"]
  Evidence --> S1["Changed file (3 files)"]
  S1 --> I1["repository behavior"]
  I1 --> Conflict["Merge conflict blocks this path"]
  Conflict --> V1["required checks"]

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Merge Conflict Guidance

• Current merge state: DIRTY
• Base branch: master
• Head branch: sentinel/csp-nonce-enhancement-17083573628632093851
• Fix direction: merge or rebase origin/master into sentinel/csp-nonce-enhancement-17083573628632093851, resolve conflict markers in the changed files, rerun the focused checks, then push the same branch.
• Repair commands:

gh pr checkout 127 --repo ContextualWisdomLab/html4tree
git fetch origin master
git merge --no-ff origin/master  # or: git rebase origin/master
git status --short
# resolve files, then git add <resolved-files>
# merge path: git commit
# rebase path: git rebase --continue
git push origin HEAD:sentinel/csp-nonce-enhancement-17083573628632093851
# rebase path only: git push --force-with-lease origin HEAD:sentinel/csp-nonce-enhancement-17083573628632093851

[opencode-agent]

Pull request overview

OpenCode reviewed the current-head bounded evidence and found no blocking issues.

Findings

No blocking findings.

Summary

Approval sufficiency: bounded evidence supplied affirmative approval evidence for changed files, coverage/docstring posture, risk surfaces, and current-head verification; approval is not based merely on the absence of known blockers.
Verification posture: CodeGraph evidence was initialized and bounded current-head evidence reviewed for changed-file evidence including .jules/sentinel.md, src/main/kotlin/html4tree/main.kt, src/test/kotlin/html4tree/MainTest.kt.
Linter/static: workflow/static review evidence is bounded by the current-head GitHub Checks gate and changed-file evidence.
TDD/regression: coverage execution evidence and focused changed hunks were reviewed from bounded-review-evidence.md.
Coverage: coverage execution evidence reports test coverage as not applicable because no supported changed source files or package manifests were found.
Docstring coverage: coverage execution evidence reports docstring coverage as not applicable because no supported changed source files or package manifests were found.
DAG: CodeGraph/source-backed behavior map connects .jules/sentinel.md to the affected review, runtime, or workflow path and required checks.
PoC/execution: coverage-evidence job executed on the current head and reported PASS.
DDD/domain: workflow and repository-governance invariants were reviewed against changed files in bounded evidence.
CDD/context: CodeGraph evidence, changed-file history, and focused hunks were reviewed from bounded-review-evidence.md.
Similar issues: changed-file history evidence was reviewed for comparable local precedents.
Claim/concept check: bounded evidence, repository source, current-head workflow evidence, and, where numeric, scientific, statistical, or literature-backed claims are affected, original-paper/formula evidence and parameter-recovery expectations were used for claims.
Standards search: standards and external-source checks are delegated to configured OpenCode web_search/Context7/DeepWiki sources when applicable; no evidence-backed standards blocker is present in bounded evidence.
Compatibility/convention: changed workflow/script conventions, object naming, and reserved-word safety for schema/API/config/code surfaces were checked in bounded evidence.
Breaking-change/backcompat: deployment evidence and changed-file history were checked for backward-compatibility risk.
Performance: changed surfaces were checked for performance risk in bounded evidence.
Developer experience: changed automation, review, test, setup, and maintenance surfaces were checked for helpful or obstructive DX impact in bounded evidence.
User experience: connected user, operator, API, CLI, documentation, review-comment, status-check, rendering, and workflow-reader behavior was checked for contradictions against code, docs, and tests in bounded evidence.
Visual/DOM: Playwright visual, DOM locator, ARIA snapshot, console, and responsive evidence were checked when a web UI surface was present; for non-web surfaces, API/CLI/log/docs/workflow interaction evidence was reviewed instead.
Accessibility/i18n: accessibility, localization, and human-readable text surfaces were checked where UI, CLI, API message, docs, logs, or review text changed.
Supply-chain/license: dependency, package, model, container, and external-tool changes were checked in bounded evidence.
Packaging: package, build, test, lint, and security contracts were checked in bounded evidence.
Security/privacy: workflow-token, review-gate, and repository-automation security/privacy boundaries were checked in bounded evidence.

• Result: APPROVE
• Reason: Security enhancement for CSP nonce implementation is correctly applied and tested
• Head SHA: b1a9b656414b3fb925e123a65a511d471c92ebf7
• Workflow run: 28975224323
• Workflow attempt: 1

Changed-File Evidence Map

flowchart LR
  PR["PR changed files"] --> Evidence["OpenCode bounded evidence"]
  Evidence --> S1["Changed file (3 files)"]
  S1 --> I1["repository behavior"]
  I1 --> R1["Review risk: Changed file (3 files)"]
  R1 --> V1["required checks"]

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[seonghobae]

@copilot resolve the merge conflicts on this branch.

[Copilot]

@copilot resolve the merge conflicts on this branch.

Merge conflicts have been resolved. The branch now incorporates all changes from master:

• src/main/kotlin/html4tree/main.kt: Kept the .dir-link and .empty-dir CSS classes from this branch, and added the @media (prefers-reduced-motion: reduce) block from master (PR 🎨 Palette: a 태그에 부드러운 호버 및 포커스 상태 전환 추가 #128).
• .jules/sentinel.md: Kept both the nonce-based CSP entry (this branch) and the information exposure entry from master (PR 🛡️ Sentinel: [보안 개선] 기본 무시 파일 목록 추가로 정보 노출 방지 #129).

All tests pass after the merge.

[opencode-agent]

Pull request overview

OpenCode reviewed the current-head mergeability evidence and changed-file flow before approval, then found merge conflicts on the affected path.

Findings

1. HIGH Merge Conflict Guidance - Resolve the PR branch against the latest base branch

• Problem: GitHub reports mergeStateStatus DIRTY for this pull request.
• Root cause: Branch sentinel/csp-nonce-enhancement-17083573628632093851 cannot be merged cleanly into master; the changed-file flow below shows which review/runtime path is blocked by the conflict.
• Fix: Merge or rebase the latest master into sentinel/csp-nonce-enhancement-17083573628632093851, resolve conflict markers in the PR branch, rerun the focused checks, and push the same branch.
• Repair commands:

gh pr checkout 127 --repo ContextualWisdomLab/html4tree
git fetch origin master
git merge --no-ff origin/master  # or: git rebase origin/master
git status --short
# resolve files, then git add <resolved-files>
# merge path: git commit
# rebase path: git rebase --continue
git push origin HEAD:sentinel/csp-nonce-enhancement-17083573628632093851
# rebase path only: git push --force-with-lease origin HEAD:sentinel/csp-nonce-enhancement-17083573628632093851

• Regression test: Keep OpenCode approval gated on mergeability so model-output failures cannot approve a conflicted PR.

Merge Conflict Evidence Map

flowchart LR
  PR["PR changed files"] --> Evidence["OpenCode bounded evidence"]
  Evidence --> S1["Changed file (3 files)"]
  S1 --> I1["repository behavior"]
  I1 --> Conflict["Merge conflict blocks this path"]
  Conflict --> V1["required checks"]

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• Result: REQUEST_CHANGES
• Reason: mergeStateStatus is DIRTY; mergeable is CONFLICTING.
• Head SHA: ae1e1c98d3663af6105bd1038e44fd66d60cd0e6
• Workflow run: 29151400012
• Workflow attempt: 1

Changed-File Evidence Map

flowchart LR
  PR["PR changed files"] --> Evidence["OpenCode bounded evidence"]
  Evidence --> S1["Changed file (3 files)"]
  S1 --> I1["repository behavior"]
  I1 --> Conflict["Merge conflict blocks this path"]
  Conflict --> V1["required checks"]

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