{"id":"CVE-2026-41894","aliases":["GHSA-hjh7-r5w8-5872"],"title":"SiYuan: Path Traversal via Double URL Encoding in `/export/` Endpoint (Incomplete Fix Bypass for CVE-2026-30869)","summary":"SiYuan: Path Traversal via Double URL Encoding in `/export/` Endpoint (Incomplete Fix Bypass for CVE-2026-30869)","severity":"high","cwe":["CWE-22"],"vendor":"siyuan-note","product":"github.com/siyuan-note/siyuan/kernel","ecosystem":"go","affected":["github.com/siyuan-note/siyuan/kernel < 3.6.5"],"patched":["github.com/siyuan-note/siyuan/kernel 3.6.5"],"published":"2026-04-22","updated":"2026-11-09","sourceUpdated":"2026-11-09T01:45:34Z","source":"GHSA","sourceUrl":"https://github.com/advisories/GHSA-hjh7-r5w8-5872","references":[{"url":"https://github.com/siyuan-note/siyuan/security/advisories/GHSA-hjh7-r5w8-5872"},{"url":"https://github.com/siyuan-note/siyuan/commit/bb481e1290c4a34255652ede85a546504505d2a7"},{"url":"https://github.com/advisories/GHSA-2h2p-mvfx-868w"},{"url":"https://github.com/siyuan-note/siyuan/releases/tag/v3.6.5"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-41894"},{"url":"https://github.com/advisories/GHSA-hjh7-r5w8-5872"}],"tags":["ghsa","go"],"epss":0.00374,"epssPercentile":0.31672,"ingestedAt":"2026-11-09T02:01:54.432Z","slug":"CVE-2026-41894","body":"## Overview\n\n### Summary\nThe fix for CVE-2026-30869 in SiYuan v3.5.10 only added a denylist check (`IsSensitivePath`) but did not address the root cause — a redundant `url.PathUnescape()` call in `serveExport()`. An authenticated attacker can use double URL encoding (`%252e%252e`) to traverse directories and read arbitrary workspace files including the full SQLite database (`siyuan.db`), kernel log, and all user documents.\n\n### Details\nIn `kernel/server/serve.go`, the `serveExport()` function (line 314-320) processes file paths as follows:\n\n```go\nfilePath := strings.TrimPrefix(c.Request.URL.Path, \"/export/\")\ndecodedPath, err := url.PathUnescape(filePath)     // second decode\nfullPath := filepath.Join(exportBaseDir, decodedPath)\n```\n\nGo's HTTP server already decodes percent-encoded characters once during request parsing. The additional `url.PathUnescape()` call creates a double-decode vulnerability:\n\n1. Attacker sends: `GET /export/%252e%252e/siyuan.db`\n2. Go HTTP decodes `%25` → `%`, result: `URL.Path = /export/%2e%2e/siyuan.db`\n3. Go's path cleaner sees `%2e%2e` as literal characters (not `..`), no redirect occurs\n4. `url.PathUnescape(\"%2e%2e\")` decodes to `..`\n5. `filepath.Join(exportBaseDir, \"../siyuan.db\")` resolves to `<workspace>/temp/siyuan.db`\n\nThe CVE-2026-30869 fix added `IsSensitivePath()` which blocks `<workspace>/conf/` and OS-level paths (`/etc`, `/root`, etc.). However, it does NOT block:\n- `<workspace>/temp/siyuan.db` — full document database\n- `<workspace>/temp/blocktree.db` — block tree database\n- `<workspace>/temp/siyuan.log` — kernel log\n- `<workspace>/temp/asset_content.db` — asset content database\n\nNote: the `/appearance/` handler in the same file correctly uses `gulu.File.IsSubPath()` to validate paths (line 447), but this check is missing from the `/export/` handler.\n\n### PoC\n[poc.zip](https://github.com/user-attachments/files/26866234/poc.zip)\nPlease extract the uploaded compressed file before proceeding\n\n1. docker compose up -d --build\n2. sh poc.sh\n\n<img width=\"550\" height=\"184\" alt=\"스크린샷 2026-04-19 오후 5 08 30\" src=\"https://github.com/user-attachments/assets/6aea4334-0b5a-4f45-bd1f-ecfad61ba524\" />\n\n\n\n\n### Impact\n- Data exfiltration: An authenticated user (including low-privilege Publish/Reader users via the Publish service) can download the entire SQLite document database containing all blocks, documents, attributes, and full-text search indexes.\n- Information disclosure: Kernel log (`siyuan.log`) leaks internal server paths, versions, configuration details, and error messages.\n\n## Affected packages\n\n- `github.com/siyuan-note/siyuan/kernel < 3.6.5`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `github.com/siyuan-note/siyuan/kernel 3.6.5`","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}