CVE-2026-29183 PoC — SiYuan: Unauthenticated reflected SVG XSS in `/api/icon/getDynamicIcon` (`type=8`) enables arbitrary JavaScript executio

Source

https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-29183.yaml

Associated Vulnerability

Title: SiYuan: Unauthenticated reflected SVG XSS in `/api/icon/getDynamicIcon` (`type=8`) enables arbitrary JavaScript execution (CVE-2026-29183)
Description:SiYuan is a personal knowledge management system. Prior to version 3.5.9, an unauthenticated reflected XSS vulnerability exists in the dynamic icon API endpoint "GET /api/icon/getDynamicIcon" when type=8, attacker-controlled content is embedded into SVG output without escaping. Because the endpoint is unauthenticated and returns image/svg+xml, a crafted URL can inject executable SVG/HTML event handlers (for example onerror) and run JavaScript in the SiYuan web origin. This can be chained to perform authenticated API actions and exfiltrate sensitive data when a logged-in user opens the malicious link. This issue has been patched in version 3.5.9.

Description

Unauthenticated reflected cross-site scripting (XSS) vulnerability in all versions of SiYuan Note containing `/api/icon/getDynamicIcon` with unsafe `type=8` rendering logic. Attacker-controlled `content` is inserted directly into SVG output without proper sanitization. An attacker can execute arbitrary JavaScript in users' browsers when they visit a crafted malicious link.

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