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GHSA-hjh7-r5w8-5872

HighCVSS 7.1 / 10
Published Apr 22, 2026·Last modified May 5, 2026
Affected Components(0)

No affected components available

Description

Summary

The 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.

Details

In kernel/server/serve.go, the serveExport() function (line 314-320) processes file paths as follows:

filePath := strings.TrimPrefix(c.Request.URL.Path, "/export/")
decodedPath, err := url.PathUnescape(filePath)     // second decode
fullPath := filepath.Join(exportBaseDir, decodedPath)

Go's HTTP server already decodes percent-encoded characters once during request parsing. The additional url.PathUnescape() call creates a double-decode vulnerability:

  1. Attacker sends: GET /export/%252e%252e/siyuan.db
  2. Go HTTP decodes %25 → %, result: URL.Path = /export/%2e%2e/siyuan.db
  3. Go's path cleaner sees %2e%2e as literal characters (not ..), no redirect occurs
  4. url.PathUnescape("%2e%2e") decodes to ..
  5. filepath.Join(exportBaseDir, "../siyuan.db") resolves to <workspace>/temp/siyuan.db

The CVE-2026-30869 fix added IsSensitivePath() which blocks <workspace>/conf/ and OS-level paths (/etc, /root, etc.). However, it does NOT block:

  • <workspace>/temp/siyuan.db — full document database
  • <workspace>/temp/blocktree.db — block tree database
  • <workspace>/temp/siyuan.log — kernel log
  • <workspace>/temp/asset_content.db — asset content database

Note: 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.

PoC

poc.zip Please extract the uploaded compressed file before proceeding

  1. docker compose up -d --build
  2. sh poc.sh
<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" />

Impact

  • 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.
  • Information disclosure: Kernel log (siyuan.log) leaks internal server paths, versions, configuration details, and error messages.
Risk Scores
Base Score
7.1

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability.

Threat Intelligence
4.9

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
0.31%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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