Is CVE-2026-31809 actively exploited?

No active exploitation of CVE-2026-31809 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2026-31809 be exploited remotely?

Yes. CVE-2026-31809 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2026-31809?

CVE-2026-31809 has a CVSS score of 6.1 (MEDIUM).

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MEDIUM

CVE-2026-31809

CWE-79Published: March 10, 2026· Updated: Mar 11, 2026

6.1

CVSS v3.1

EPSS:0.03%probability of exploitation in 30 daysPercentile:7.7th

Official 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.

NVD Source

Technical Analysis

CVE-2026-31809 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation does not require any privileges, though user interaction (Required) is needed, which slightly reduces the risk of mass automated attacks.

The vulnerability has a "Changed" scope, meaning successful exploitation can impact components beyond the vulnerable component itself — such as the host operating system or adjacent services.

From a weakness classification perspective (CWE-79): Cross-site scripting (XSS) vulnerabilities allow attackers to inject malicious scripts into web pages viewed by other users.