Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2026-31807

Severity CVSS v4.0:
MEDIUM
Type:
CWE-79 Cross-Site Scripting (XSS)
Publication date:
10/03/2026
Last modified:
11/03/2026

Description

SiYuan is a personal knowledge management system. Prior to 3.5.10, SiYuan's SVG sanitizer (SanitizeSVG) blocks dangerous elements (, , ) and removes on* event handlers and javascript: in href attributes. However, it does NOT block SVG animation elements (, ) which can dynamically set attributes to dangerous values at runtime, bypassing the static sanitization. This allows an attacker to inject executable JavaScript into the unauthenticated /api/icon/getDynamicIcon endpoint (type=8), creating a reflected XSS. This is a bypass of the fix for CVE-2026-29183 (fixed in v3.5.9). This vulnerability is fixed in v3.5.10.

Impact

Vector 4.0
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N CVSS v4.0 Severity and Metrics:

Base Score: 6.40 MEDIUM
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N

Attack Vector (AV): Network
Attack Complexity (AC): Low
Attack Requirements (AT): None
Privileges Required (PR): None
User Interaction (UI): Passsive
Confidentiality (VC): None
Integrity (VI): None
Availability (VA): None
Confidentiality (SC): High
Integrity (SI): High
Availability (SA): None

Base Score 4.0
6.40
Severity 4.0
MEDIUM
Vector 3.x
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N CVSS v3.1 Severity and Metrics:

Base Score: 6.10 MEDIUM
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): Required
Scope (S): Changed
Confidentiality (C): Low
Integrity (I): Low
Availability (A): None

Base Score 3.x
6.10
Severity 3.x
MEDIUM

Vulnerable products and versions

CPE From Up to
cpe:2.3:a:b3log:siyuan:*:*:*:*:*:*:*:* 3.5.10 (excluding)

To consult the complete list of CPE names with products and versions, see this page


References to Advisories, Solutions, and Tools