🛡️ Sentinel: [CRITICAL] 심볼릭 링크 우회(Path Traversal) 취약점 수정

[seonghobae]

🚨 Severity: CRITICAL
💡 Vulnerability: go 함수에서 File(topDir).canonicalFile을 호출하여 먼저 실제 대상 경로로 변환한 후, LinkOption.NOFOLLOW_LINKS 옵션으로 디렉토리 여부를 검증하고 있었습니다. 이로 인해 심볼릭 링크를 입력해도 항상 실제 대상 경로를 기준으로 검사하게 되어 제한이 우회되었습니다.
🎯 Impact: 사용자가 의도치 않게 심볼릭 링크를 사용하여 제한된 상위 경로나 시스템의 다른 파일/디렉토리 구조(Path Traversal)에 접근할 위험이 있습니다.
🔧 Fix: canonicalFile로 변환하기 전 원본 File 객체를 먼저 검사하여 심볼릭 링크인 경우 예외를 발생시키도록 수정했습니다.
✅ Verification: ./gradlew test jacocoTestReport를 실행하여 100% 코드 커버리지를 만족하는지 및 testGoRejectsSymlinkTopDir 테스트가 성공하는지 확인 완료했습니다.

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PR created automatically by Jules for task 5712274623037379069 started by @seonghobae

[google-labs-jules]

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[Copilot]

Pull request overview

This PR addresses a critical symlink-based path traversal bypass in go() by ensuring the “top directory must be a real directory” validation is performed on the original user-supplied path before any canonicalization resolves symlinks.

Changes:

• Validate topDir with Files.isDirectory(..., LinkOption.NOFOLLOW_LINKS) before calling canonicalFile to prevent symlink-root bypass.
• Update .jules/sentinel.md with a new entry describing the symlink-check bypass learning.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/main/kotlin/html4tree/main.kt	Reorders top directory validation to occur before canonicalization, preventing symlink-root traversal bypass.
.jules/sentinel.md	Adds a new sentinel entry about the vulnerability (but currently overwrites prior history).

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[github-actions]

Pull request overview

OpenCode reviewed the current-head evidence but found unresolved reviewer or review-agent threads before approval.

Findings

1. HIGH .github/workflows/opencode-review.yml:1 - Unresolved reviewer thread blocks automated approval

• Problem: OpenCode reached an APPROVE control result, but the approval step found unresolved, non-outdated human or review-agent thread evidence on the current pull request.
• Root cause: Reviewer and review-agent feedback can arrive after bounded model evidence is prepared, so the approval step must re-query GitHub immediately before publishing an approval.
• Fix: Address or resolve the listed reviewer thread(s), then re-run OpenCode on the current head.
• Regression test: Keep the approval gate querying reviewThreads(first: 100) after model output and before create_pull_review APPROVE, including bot review agents other than OpenCode itself.

Review thread evidence

Latest unresolved reviewer thread evidence

.jules/sentinel.md line 4

• Latest reviewer comment: @copilot-pull-request-reviewer at 2026-07-01T20:55:34Z

• Comment URL: #76 (comment)

• Comment excerpt: This edit replaces the entire '.jules/sentinel.md' history with a single entry, which discards previously recorded security learnings. The other '.jules/*.md' files (e.g., '.jules/palette.md') retain prior entries and append new ones, so this looks like accidental data loss rather than an intentional update. / Consider restoring the existing entries and adding this new 2024-07-01 entry in addition (append or prepend), so the sentinel log remains cumulative.

• Result: REQUEST_CHANGES

• Reason: unresolved reviewer or review-agent thread(s) were present before approval.

• Head SHA: 8afed0b1872e23f2806dd5d60619eda2a41daa69

• Workflow run: 28547068065

• Workflow attempt: 1

Changed-File Evidence Map

flowchart LR
  PR["PR changed files"] --> Evidence["OpenCode bounded evidence"]
  Evidence --> S1["Changed file (2 files)"]
  S1 --> I1["repository behavior"]
  I1 --> R1["Review risk: Changed file (2 files)"]
  R1 --> V1["required checks"]

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[github-actions]

OpenCode Review Overview

• Head SHA: 8afed0b1872e23f2806dd5d60619eda2a41daa69
• Workflow run: 28547068065
• Workflow attempt: 1
• Gate result: REQUEST_CHANGES (approval step)

Pull request overview

OpenCode reviewed the current-head evidence but found unresolved reviewer or review-agent threads before approval.

Findings

1. HIGH .github/workflows/opencode-review.yml:1 - Unresolved reviewer thread blocks automated approval

• Problem: OpenCode reached an APPROVE control result, but the approval step found unresolved, non-outdated human or review-agent thread evidence on the current pull request.
• Root cause: Reviewer and review-agent feedback can arrive after bounded model evidence is prepared, so the approval step must re-query GitHub immediately before publishing an approval.
• Fix: Address or resolve the listed reviewer thread(s), then re-run OpenCode on the current head.
• Regression test: Keep the approval gate querying reviewThreads(first: 100) after model output and before create_pull_review APPROVE, including bot review agents other than OpenCode itself.

Review thread evidence

Latest unresolved reviewer thread evidence

.jules/sentinel.md line 4

• Latest reviewer comment: @copilot-pull-request-reviewer at 2026-07-01T20:55:34Z

• Comment URL: 🛡️ Sentinel: [CRITICAL] 심볼릭 링크 우회(Path Traversal) 취약점 수정 #76 (comment)

• Comment excerpt: This edit replaces the entire '.jules/sentinel.md' history with a single entry, which discards previously recorded security learnings. The other '.jules/*.md' files (e.g., '.jules/palette.md') retain prior entries and append new ones, so this looks like accidental data loss rather than an intentional update. / Consider restoring the existing entries and adding this new 2024-07-01 entry in addition (append or prepend), so the sentinel log remains cumulative.

• Result: REQUEST_CHANGES

• Reason: unresolved reviewer or review-agent thread(s) were present before approval.

• Head SHA: 8afed0b1872e23f2806dd5d60619eda2a41daa69

• Workflow run: 28547068065

• Workflow attempt: 1

Changed-File Evidence Map

flowchart LR
  PR["PR changed files"] --> Evidence["OpenCode bounded evidence"]
  Evidence --> S1["Changed file (2 files)"]
  S1 --> I1["repository behavior"]
  I1 --> R1["Review risk: Changed file (2 files)"]
  R1 --> V1["required checks"]

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