VulnerabilityPublished 6 Feb 2026Updated 9 Feb 2026

CVE-2026-25647: siyuan · Cross-site Scripting

Affects siyuanSource CVE Database V5

Not known to be exploited · CVSS 4.6 Medium : upgrade to 3.5.5 when convenient.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score

4.6Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 14% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 3.5.5

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: Required
Scope: Unchanged
Confidentiality: Low
Integrity: Low
Availability: None

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

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, 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: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 6 Feb 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 3.5.5.

Affected software

Product	Affected	Fixed in
siyuan-notesiyuan	Affected <3.5.5	Fixed in 3.5.5
GitHubsiyuan-note/siyuan`pkg:github/siyuan-note/siyuan`Other threats	Affected <3.5.5	Fixed in 3.5.5

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 3.5.5 or later, where this vulnerability is addressed. Until upgrading, restrict note creation and editing permissions to trusted users only to minimize injection risk. Implement input validation and sanitization on Markdown content at the application level to neutralize potentially malicious scripts. Employ Content Security Policy (CSP) headers to limit the execution of unauthorized scripts in browsers. Monitor logs for unusual note content submissions or user activity indicative of exploitation attempts. Educate users to be cautious when interacting with notes from untrusted sources, especially avoiding clicking suspicious links or content. Regularly audit and review collaboration platform configurations and user permissions to enforce the principle of least privilege. Finally, maintain an incident response plan to quickly address any detected exploitation.

Description

Lute is a structured Markdown engine supporting Go and JavaScript. Lute 1.7.6 and earlier (as used in SiYuan before) has a Stored Cross-Site Scripting (XSS) vulnerability in the Markdown rendering engine. An attacker can inject malicious JavaScript into a Markdown text/note. When another user clicks the rendered content, the script executes in the context of their session.

Impact

For European organizations, this vulnerability could lead to unauthorized disclosure of sensitive information such as session cookies or user credentials if exploited, enabling further attacks like session hijacking or privilege escalation within the affected application. The integrity of note content can also be compromised, potentially misleading users or injecting malicious payloads into internal communications. Although availability is not impacted, the breach of confidentiality and integrity can undermine trust in collaboration platforms. Organizations using siyuan-note for knowledge management, documentation, or team collaboration are at risk, especially if untrusted users or external collaborators have note editing permissions. The medium severity rating reflects that exploitation requires some user interaction and privileges, limiting the scope but not eliminating risk. The absence of known exploits reduces immediate threat but does not preclude future attacks. European entities with strict data protection regulations (e.g., GDPR) must consider the risk of data leakage and reputational damage.

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #1OWASP Top 10 A05:2025: Injection (opens in a new tab)
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Implementation · Architecture and Design
Understand the context in which your data will be used and the encoding that will be expected. This is especially important when transmitting data between different components, or when generating outputs that can contain multiple encodings at the same time, such as web pages or multi-part mail messages.
Architecture and Design · Implementation · Attack Surface Reduction
Understand all the potential areas where untrusted inputs can enter your software: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide…
OWASP Cheat Sheets
Cross Site Scripting Prevention (opens in a new tab)
DOM based XSS Prevention (opens in a new tab)
Injection Prevention (opens in a new tab)
Abuse Case (opens in a new tab)
Deserialization (opens in a new tab)
OWASP ASVS 4.0.3
V5.3.3 (opens in a new tab)
V1.5.1 (opens in a new tab)
Attack patterns
XSS Using MIME Type Mismatch (opens in a new tab)
DOM-Based XSS (opens in a new tab)
Reflected XSS (opens in a new tab)
Stored XSS (opens in a new tab)
Cross-Site Scripting (XSS) (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 14 Feb 2026, 12:11 UTC

WeaknessesCWE-79

Technical details

References

Community reviews

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