9.4

CVSS Score

4.0

-

CVSS Score

Basic Information

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CVE-2026-22813

CVE-2026-22813: Malicious website can execute commands on the local system through XSS in the OpenCode web UI

OpenCode is an open source AI coding agent. The markdown renderer used for LLM responses will insert arbitrary HTML into the DOM. There is no sanitization with DOMPurify or even a CSP on the web interface to prevent JavaScript execution via HTML injection. This means controlling the LLM response for a chat session gets JavaScript execution on the http://localhost:4096 origin. This vulnerability is fixed in 1.1.10.

(GitHub Advisory)

Miggo Vulnerability Database

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CVE-2026-22813

CVE-2026-22813:

9.4

CVSS Score

4.0

-

CVSS Score

Basic Information

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Technical Details

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
opencode-ai	npm	< 1.1.10	1.1.10

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability is an XSS issue in the OpenCode web UI, leading to local command execution. The core of the vulnerability is in the packages/app/src/app.tsx file, where the defaultServerUrl function takes a url parameter from the query string without any validation. An attacker can craft a URL to trick a user into loading a malicious chat session from an attacker-controlled server. The chat session contains a javascript payload in a markdown message, which is rendered without sanitization, leading to XSS on the localhost origin. From there, the javascript payload can use the /pty/ API to execute arbitrary commands on the user's machine. The provided patch commit is a release commit that bumps the package versions to 1.1.10. The vulnerability description states that this version disables the web UI, which is the mitigation for this vulnerability. Therefore, the vulnerable function defaultServerUrl is identified from the description of the vulnerability itself.

Vulnerable functions

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WAF Protection Rules

WAF Rule

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Reasoning

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