VulnerabilityPublished 19 Jan 2026Updated 20 Jan 2026

CVE-2026-23851: siyuan · Path Traversal

Affects siyuanSource CVE Database V5

Not known to be exploited · CVSS 8.3 High : upgrade to 3.5.4 soon.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 4.0 base score

8.3High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.5% chance of exploitation in 30 days – higher than 43% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 3.5.4

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: Low
User Interaction: None
Vulnerable system confidentiality: High
Vulnerable system integrity: None
Vulnerable system availability: None
Subsequent system confidentiality: High
Subsequent system integrity: None
Subsequent system availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: Low: The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: High: There is a total loss of confidentiality, resulting in all information within the Vulnerable System being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: None: There is no impact to availability within the Vulnerable System.
Subsequent system confidentiality: High: There is a total loss of confidentiality, resulting in all resources within the Subsequent System being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 19 Jan 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade siyuan and siyuan-note/siyuan to 3.5.4.

Affected software

Product	Affected	Fixed in
siyuan-notesiyuan	Affected <3.5.4	Fixed in 3.5.4
GitHubsiyuan-note/siyuan`pkg:github/siyuan-note/siyuan`Other threats	Affected <3.5.4	Fixed in 3.5.4

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

European organizations should immediately upgrade SiYuan Note installations to version 3.5.4 or later, where this vulnerability is patched. Until the upgrade is applied, restrict access to the /api/file/globalCopyFiles endpoint by implementing strict access controls and monitoring authenticated user activities for unusual file copy requests. Employ network segmentation to limit exposure of SiYuan servers to trusted users only. Conduct regular audits of user accounts and credentials to minimize risks from compromised or malicious insiders. Implement file integrity monitoring within the workspace directory to detect unauthorized file additions or changes. Additionally, consider deploying Web Application Firewalls (WAFs) with custom rules to detect and block suspicious path traversal patterns in API requests. Finally, educate users on the importance of credential security and monitor logs for signs of exploitation attempts. These targeted measures will reduce the attack surface and help detect or prevent exploitation beyond generic patching advice.

Description

CVE-2026-23851 is a high-severity path traversal vulnerability in SiYuan Note versions prior to 3.5.4. It affects the /api/file/globalCopyFiles endpoint, allowing authenticated users to copy arbitrary files from anywhere on the server into the application's workspace due to insufficient path validation. The vulnerability arises because the code verifies file existence but does not restrict source paths to authorized directories. Exploitation requires authentication but no user interaction and can lead to unauthorized file access and potential data leakage or manipulation. The issue is patched in version 3.5.4. European organizations using affected SiYuan versions should prioritize upgrading to mitigate risks.

Impact

For European organizations using SiYuan Note versions prior to 3.5.4, this vulnerability poses a significant risk of unauthorized file access and data leakage. Attackers with valid credentials could exploit this flaw to copy sensitive files from the server's filesystem into the application's workspace, potentially exposing confidential information or intellectual property. This could lead to breaches of data protection regulations such as GDPR if personal or sensitive data is accessed or exfiltrated. Additionally, the integrity of the knowledge management system could be compromised by injecting or manipulating files within the workspace, disrupting business operations or causing misinformation. Since the vulnerability requires authentication, insider threats or compromised credentials increase the risk. The high CVSS score reflects the potential for serious confidentiality and integrity impacts, although availability is not directly affected. Organizations relying on SiYuan for critical knowledge management should consider this vulnerability a priority for remediation to prevent potential exploitation and compliance violations.

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #6OWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Architecture and Design
For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks…
Implementation · Input Validation
Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174).
OWASP Cheat Sheets
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V12.3.1 (opens in a new tab)
Attack patterns
Path Traversal (opens in a new tab)
Using Slashes and URL Encoding Combined to Bypass Validation Logic (opens in a new tab)
Manipulating Web Input to File System Calls (opens in a new tab)
Using Escaped Slashes in Alternate Encoding (opens in a new tab)
Using Slashes in Alternate Encoding (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 27 Jan 2026, 20:23 UTC

WeaknessesCWE-22

Technical details

References

Community reviews

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