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Critical, CVSS 9.4amended

Malicious website can execute commands on the local system through XSS in the OpenCode web UI

CVE-2026-22813GHSA-c83v-7274-4vgp

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (opencode-ai 1.1.10), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
9.4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H · score source
EPSS
  • CVE-2026-22813: 0.91% estimated exploitation activity in the next 30 days; percentile 59.87 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary A malicious website can abuse the server URL override feature of the OpenCode web UI to achieve cross-site scripting on http://localhost:4096. From there, it is possible to run arbitrary commands on the local system using the /pty/ endpoints provided by the OpenCode API. Code execution via OpenCode API - The OpenCode API has /pty/ endpoints that allow spawning arbitrary processes on the local machine. - When you run opencode in your terminal, OpenCode automatically starts an HTTP server on localhost:4096 that exposes the API along with a web interface. - JavaScript can make arbitrary same-origin fetch() requests to the /pty/ API endpoints. Therefore, JavaScript execution on http://localhost:4096 gets you code execution on local the machine. JavaScript execution on localhost:4096 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…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 4 · amended ·

    Amended from ghsa record GHSA-c83v-7274-4vgp

  2. Revision 3 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  3. Revision 2 · amended ·

    Amended from osv record GHSA-c83v-7274-4vgp

  4. Revision 1 · created ·

    Published from ghsa record GHSA-c83v-7274-4vgp

Agent brief

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# Patch Next advisory brief: CVE-2026-22813

Advisory: Malicious website can execute commands on the local system through XSS in the OpenCode web UI
IDs: CVE-2026-22813, GHSA-c83v-7274-4vgp
Record: https://patchnext.com/advisories/cve-2026-22813 (revision 4, source checked 26 Oct 2026, 12:41 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: opencode-ai 1.1.10. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm opencode-ai: affected < 1.1.10; fixed in 1.1.10

## Suggested inspection (read-only)
- `npm ls opencode-ai --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on opencode-ai.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-c83v-7274-4vgp (GitHub-reviewed advisory GHSA-c83v-7274-4vgp lists affected ranges: npm opencode-ai >=0 <1.1.10)
- Verified: https://osv.dev/vulnerability/GHSA-c83v-7274-4vgp (OSV record GHSA-c83v-7274-4vgp lists affected ranges: npm opencode-ai >=0 <1.1.10 (fixed))

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