Medium File handling

CVE-2026-116171 — SiYuan 3.5.4 before 3.8.7 Sensitive Path Bypass via Windows Extended-Length Prefix

SiYuan 3.5.4 before 3.8.7 on Windows contains a sensitive-path denylist bypass in IsSensitivePath because the Windows extended-length prefix (\\?\) survives filepath.Clean and matches no forbidden prefix. Authenticated API callers can prepend the prefix to localPath in /api/import/importStdMd to copy workspace conf files, including the API token and TLS private keys, into assets served to unauthenticated clients.

Published Oct 25, 2026 · Updated Oct 28, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: VulnCheck

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.5% (30-day exploitation probability)+6
Technical severity (medium)+3
Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.48%

ahead of 41% of scored CVEs · Oct 29, 2026

Affects

Siyuan-note

Siyuan

CVSS base

4.4

Medium · 3 source(s)

Prioritization reference: 7.5 provisional

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

Yes

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Siyuan-note Siyuan).
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes matching the vulnerability class (file handling), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Siyuan-note	Siyuan	≥ 3.5.4 and < 3.8.7	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

High

Privileges required

High

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
5.9	CVSS 4.0	Medium	—	—	disclosure@vulncheck.com via NIST National Vulnerability Database
5.9	CVSS 4.0	Medium	—	—	VulnCheck via CVE Program (cve.org) e CISA ADP
7.5	CVSS 3.1	High	—	—	GitHub, Inc. via GitHub Security Advisories
4.4	CVSS 3.1	Medium	0.7	3.6	disclosure@vulncheck.com via NIST National Vulnerability Database
4.4	CVSS 3.1	Medium	—	—	VulnCheck via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:N/A:N (score shown at the top: disclosure@vulncheck.com)

Sources disagree significantly and the divergence is under review. Every score is kept with its origin. For prioritization we use 7.5 (GitHub, Inc. via GitHub Security Advisories) as a conservative provisional reference — not a definitive official score.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-22 · Path Traversal

Other CVEs with this weakness →

EPSS over time FIRST

Oct 26, 2026 → Oct 29, 2026 · 4 reading(s) · max 0.56%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Monitor file creation in web directories and paths with traversal sequences (../).

web/proxy/WAF logsnetwork IDS/IPSfile integrity (FIM)endpoint telemetry (EDR)

Timeline

What happened to this CVE, newest first.

2026
CVSS changed · 7.5 → 4.4
Oct 28, 2026 · NIST National Vulnerability Database
SSVC assessment updated
Oct 26, 2026 · CVE Program (cve.org) e CISA ADP
Affected products added · siyuan-note/siyuan
Oct 25, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 25, 2026
CVSS changed · 7.5
Oct 25, 2026 · NIST National Vulnerability Database
Source status changed · → Deferred
Oct 25, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 25, 2026 · Alertas do Telegram
CVE published
Oct 25, 2026 · VulnCheck

Source activity

Repeated readings are counted rather than listed.

2× References added · Oct 25, 2026 – Oct 26, 2026
1× Official description updated · Oct 25, 2026 – Oct 25, 2026

References

4 on the record

github.com/advisories/GHSA-6xx3-j82h-hmgh
GitHub Security Advisories
github.com/siyuan-note/siyuan/security/advisories/GHSA-6gmc-424x-xgpm
vendor-advisory, NIST National Vulnerability Database
www.vulncheck.com/advisories/siyuan-3.5.4-before-3.8.7-sensitive-path-bypass-via-window
third-party-advisory, NIST National Vulnerability Database
nvd.nist.gov/vuln/detail/CVE-2026-116171
GitHub Security Advisories

Elsewhere on this site

Siyuan-note
every CVE for this vendor

File handling
same class

CWE-22
other pages naming this weakness

Related CVEs (same products)

Medium CVE-2026-118680 SiYuan 3.8.7 through 3.8.8 Path Traversal via GLOBALROOT Alias 2d
Medium CVE-2026-116169 SiYuan 2.10.0 before 3.8.7 Stored XSS via KaTeX \href in Math Blocks 5d
Medium CVE-2026-116170 SiYuan before v3.8.7 SQL Injection via History Search op and query 5d
Medium CVE-2026-116167 SiYuan 2.9.0 before 3.8.7 XSS via check-auth to Parameter 5d
Medium CVE-2026-116168 SiYuan before v3.8.7 Path Traversal Local File Read via MCP Asset Tool 5d
Medium CVE-2026-116166 SiYuan 3.6.0 before 3.8.7 Cleartext Transmission via Unenforced networkServeTLS Setting 5d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-116171 is "SiYuan 3.5.4 before 3.8.7 Sensitive Path Bypass via Windows Extended-Length Prefix", rated Medium. It affects Siyuan (Siyuan-note); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 4.4 describes technical severity. EPSS 0.48% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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