SiYuan-Note SiYuan up to 3.8.1 Notebook Template cross site scripting

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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5.3$0-$5k0.00+

Summaryinfo

A vulnerability classified as problematic has been found in SiYuan-Note SiYuan up to 3.8.1. This affects an unknown function of the component Notebook Template. Performing a manipulation results in cross site scripting. This vulnerability was named CVE-2026-87811. The attack may be initiated remotely. There is no available exploit. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, was found in SiYuan-Note SiYuan up to 3.8.1. This affects some unknown processing of the component Notebook Template. The manipulation with an unknown input leads to a cross site scripting vulnerability. CWE is classifying the issue as CWE-79. 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. This is going to have an impact on integrity. The summary by CVE is:

SiYuan before v3.8.2 inserts persisted notebook template paths into HTML input value attributes without proper attribute encoding. Attackers can craft malicious template paths that break out of the attribute context and execute JavaScript when a victim opens notebook configuration, enabling same-origin API requests and application state manipulation.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-87811 since 09/09/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. It demands that the victim is doing some kind of user interaction. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1059.007 for this issue.

Upgrading to version 3.8.2 eliminates this vulnerability.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Vendor

Name

Version

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 5.4
VulDB Meta Temp Score: 5.3

VulDB Base Score: 3.5
VulDB Temp Score: 3.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.3
CNA Vector (VulnCheck): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Cross site scripting
CWE: CWE-79 / CWE-94 / CWE-74
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: SiYuan 3.8.2

Timelineinfo

09/09/2026 Advisory disclosed
09/09/2026 +0 days CVE reserved
09/09/2026 +0 days VulDB entry created
09/09/2026 +0 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-87811 (🔒)
GCVE (CVE): GCVE-0-2026-87811
GCVE (VulDB): GCVE-100-401673

Entryinfo

Created: 09/09/2026 13:41
Changes: 09/09/2026 13:41 (76)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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