The vulnerability is a client‑side DOM XSS flaw in the Dify web chat application that occurs when echarts components are used to render charts. Because the frontend does not properly sanitize or encode user‑or‑LLM‑generated inputs that feed into echarts, an attacker can embed malicious JavaScript payloads that are executed in the browser when the chart is rendered. This flaw is identified as CWE‑79.

Affected systems are versions of the Dify open‑source LLM application produced by langgenius before release 1.13.0. The flaw resides in the chat frontend code that processes dynamic input. Users running Dify distributions older than 1.13.0 should be aware that any chat interface making use of echarts for graph rendering is vulnerable.

The severity score for this issue is 5.3 on the CVSS v3.1 scale, indicating moderate impact. The probability of exploitation, as suggested by an EPSS score of less than 1%, is very low, and the vulnerability has not been reported as a known exploited vulnerability in the CISA KEV catalog. Exploitation requires an attacker to supply crafted input to the chat interface, typically by influencing a user or LLM to produce code that will be rendered by echarts; the attack vector is client‑side and relies on user interaction.