CVE & CISA-KEV Catalog

CVE-2026-31809

MEDIUM
6.1
CVSS v3
NVD

Description

SiYuan is a personal knowledge management system. Prior to 3.5.10, SiYuan's SVG sanitizer (SanitizeSVG) checks href attributes for the javascript: prefix using strings.HasPrefix(). However, inserting ASCII tab (	), newline (
), or carriage return (
) characters inside the javascript: string bypasses this prefix check. Browsers strip these characters per the WHATWG URL specification before parsing the URL scheme, so the JavaScript still executes. This allows an attacker to inject executable JavaScript into the unauthenticated /api/icon/getDynamicIcon endpoint, creating a reflected XSS. This is a second bypass of the fix for CVE-2026-29183 (fixed in v3.5.9). This vulnerability is fixed in 3.5.10.

CWE-79Cross-Site Scripting (XSS)

How to fix

Remediation Available
siyuanNVD
Affected:< 3.5.10Fixed in:3.5.10CVE-2026-31809derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone
User InteractionRequired
ScopeChanged

Impact

ConfidentialityLow
IntegrityLow
AvailabilityNone

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

Exploit Intelligence

0.51%probability of exploitation in 30 days
40thpercentile

Low risk: more likely to be exploited than 40% of all known CVEs.

References

Exploit1

Related Vulnerabilities

Other CWE-79 (Cross-Site Scripting (XSS)) vulnerabilities, ordered by exploit likelihood. View all

CVESeverityCVSSEPSSExploitedFix
CVE-2020-11022Medium6.999%-Fix
CVE-2019-3929Critical9.899%KEVFix
CVE-2020-9496Medium6.199%--
CVE-2023-28341Medium6.199%-Fix
CVE-2018-12998Medium6.198%--
CVE-2025-4123High7.698%-Fix
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Markdown

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HTML

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-03-11.