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

Description

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.

CVSS vector

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

Attack vector

Network

Complexity

Low

Privileges

None

User interaction

Required

Confidentiality

Low

Integrity

Low

Availability

None

Scope

Changed

Exploitation

Is it being used?

Exploit prediction (EPSS)0.9% · higher than 60% of CVEs

Exploited in the wildNo evidence yet

CISA KEVNot listed

Ransomware campaign useNot known

Affected products

Which versions

OP

opencode · anomalyco

< 1.1.10 · source: vendor, NVD