CVE-2026-85580

SiYuan before v3.8.2 Path Guard Bypass via Case Mismatch

7.1 High

SiYuan versions before v3.8.2 contain a path guard bypass vulnerability in the MCP file-access handler that uses case-sensitive matching on Linux filesystems. Attackers can read the protected publishAccess.json file by requesting case-variant paths like PublishAccess.json to disclose sensitive publish-access configuration and metadata.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: Low
Privileges needed: Low
User interaction: None

What an attacker can affect

Confidentiality: High
Integrity: None
Availability: None

Exploit likelihood

0.58%Up 0.1 points since Sep 5, 2026

What each source reports

CVE List Score used7.1

SiYuan before v3.8.2 Path Guard Bypass via Case Mismatch

Record: CVE-2026-85580
CVSS 4.0: 7.1 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
CVSS 3.1: 6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Weakness: CWE-22
Updated: 2026-11-02

EUVDEUVD-2026-710037.1

Record: EUVD-2026-71003
CVSS 4.0: 7.1 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
Updated: 2026-11-02

GitHub AdvisoriesGHSA-gwmf-gvp9-fcc27.1

SiYuan versions before v3.8.2 contain a path guard bypass vulnerability in the MCP file-access...

Record: GHSA-gwmf-gvp9-fcc2
CVSS 4.0: 7.1 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1: 6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Weakness: CWE-22
Updated: 2026-11-02

NVD7.1

Record: CVE-2026-85580
CVSS 4.0: 7.1 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1: 6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Weakness: CWE-22
Updated: 2026-11-02

OSV7.1

SiYuan before v3.8.2 Path Guard Bypass via Case Mismatch

Record: CVE-2026-85580
CVSS 4.0: 7.1 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
Weakness: CWE-22
Updated: 2026-11-02

Affected products

siyuan-note siyuan

History

History
Recorded	Changed	Sources
Nov 2, 2026	first indexed	CVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-85580 is a high vulnerability (CVSS 7.1) in Siyuan-note Siyuan, published September 4, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.58%, the 48th percentile. No source names a fixed version.