SiYuan has Arbitrary File Write via /api/file/copyFile leading to RCE
Priority HIGH 74CWE-22Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- High
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub.
Summary
SiYuan is a personal knowledge management system. Prior to version 3.5.5, the /api/file/copyFile endpoint does not validate the dest parameter, allowing authenticated users to write files to arbitrary locations on the filesystem. This can lead to Remote Code Execution (RCE) by writing to sensitive locations such as cron jobs, SSH authorized_keys, or shell configuration files. This issue has been patched in version 3.5.5.
Why it matters now
Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.01105 65th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed siyuan (siyuan-note): 3.5.5
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| siyuan-note | siyuan | before 3.5.5 | 3.5.5 | Patch available | CNA |
| — | github.com/siyuan-note/siyuan/kernel (Go) | up to 0.0.0-20260126094835-d5d10dd41b0c | — | No fix listed | GHSA-c4jr-5q7w-f6r9 |
- siyuan Vendorsiyuan-note Affected before 3.5.5 Fixed in 3.5.5 Patch available CNA
- github.com/siyuan-note/siyuan/kernel (Go) Vendor— Affected up to 0.0.0-20260126094835-d5d10dd41b0c Fixed in — No fix listed GHSA-c4jr-5q7w-f6r9
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:b3log:siyuan:*:*:*:*:*:*:*:* | up to 3.5.3 | Vulnerable | siyuan-note |
- cpe:2.3:a:b3log:siyuan:*:*:*:*:*:*:*:* Versions up to 3.5.3 Vulnerable ·siyuan-note
Remediation
- Fix · CNA siyuan (siyuan-note) Fixed in 3.5.5
Timeline
- 2026-10-02 Threatist record created from CVE-2026-25539
- 2026-10-03 Alias added: GHSA-c4jr-5q7w-f6r9
References
More siyuan-note Siyuan vulnerabilities
- TI-2026-26050 SiYuan has directory traversal within its publishing service CVSS 3.1CRITICAL 9.8
- TI-2026-25256 SiYuan: Authorization Bypass Allows Arbitrary SQL Execution via Search API CVSS 3.1CRITICAL 9.8
- TI-2024-35827 A SQL injection vulnerability was discovered in Siyuan 3.1.11 in /getHistoryItems. CVSS 3.1CRITICAL 9.8
- TI-2024-35826 A SQL injection vulnerability has been identified in Siyuan 3.1.11 via the ids array parameter in /batchGetBlockAttrs. CVSS 3.1CRITICAL 9.8
- TI-2024-35825 A SQL injection vulnerability has been identified in Siyuan 3.1.11 via the id parameter at /getAssetContent. CVSS 3.1CRITICAL 9.8
- TI-2024-35824 A SQL injection vulnerability has been identified in Siyuan 3.1.11 via the notebook parameter in /searchHistory. CVSS 3.1CRITICAL 9.8
Sources
- CVE-2026-25539 · CVE Program
- CVE-2026-25539 · NVD
- FIRST EPSS
- GHSA-c4jr-5q7w-f6r9 · GitHub Advisory Database · CC BY 4.0
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