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CVE-2026-85580— SiYuan before v3.8.2 Path Guard Bypass via Case Mismatch

Quick assessment

Affected
siyuan-note siyuan
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

思元（SiYuan）v3.8.2 之前的版本存在一个路径防护绕过漏洞，该漏洞存在于 MCP 文件访问处理器中，且在 Linux 文件系统上使用区分大小写的匹配方式。攻击者可以通过请求大小写变体的路径（例如 ）来读取受保护的 文件，从而泄露敏感的发布访问配置和元数据。

CVSS 6.5 · Medium

Affected Version Matrix 2

VendorProduct Version RangeStatus
siyuan-note siyuan < 3.8.2 affected
3.8.2 unaffected
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I. Basic Information for CVE-2026-85580

Vulnerability Information
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Vulnerability Title
SiYuan before v3.8.2 Path Guard Bypass via Case Mismatch
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
对路径名的限制不恰当(路径遍历)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
siyuan-note siyuan 0 ~ 3.8.2 -

II. Public POCs for CVE-2026-85580

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III. Intelligence Information for CVE-2026-85580

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Vendor Advisories for CVE-2026-85580 (2)

Same Patch Batch · siyuan-note · 2026-09-04 · 8 CVEs total

CVE-2026-85584 7.5 HIGH SiYuan before v3.8.2 Denial of Service via Auth Throttle
CVE-2026-85581 7.5 HIGH SiYuan before v3.8.2 Denial of Service via unauthenticated UI-process registration
CVE-2026-85585 7.5 HIGH SiYuan before v3.8.2 Unbounded Memory Consumption via ControlConcurrency
CVE-2026-85578 6.5 MEDIUM SiYuan through 3.8.1 Authorization Bypass via getFile
CVE-2026-85583 6.5 MEDIUM SiYuan before v3.8.2 Path Traversal via symlink in file API
CVE-2026-85582 6.5 MEDIUM SiYuan before v3.8.2 Unbounded Session Creation via Basic Auth
CVE-2026-85579 4.3 MEDIUM SiYuan before v3.8.2 Information Disclosure via undoState

IV. Related Vulnerabilities

Same product: siyuan
Same vendor: siyuan-note
Same weakness: CWE-22

V. Comments for CVE-2026-85580

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