{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "agents"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.3.10"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [],
  "database_specific": {
    "cwe_ids": [
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-02-13T21:04:00Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "## Summary\n\nA Reflected Cross-Site Scripting (XSS) vulnerability was discovered in the AI Playground\u0027s OAuth callback handler. The error_description query parameter was directly interpolated into an HTML script tag without proper escaping, allowing attackers to execute arbitrary JavaScript in the context of the victim\u0027s session.\n\n### Root cause\n\nThe OAuth callback handler in `site/ai-playground/src/server.ts` directly interpolated the `authError` value, sourced from the `error_description` query parameter,  into an inline `\u003cscript\u003e` tag.\n\n### Impact\n\nAn attacker could craft a malicious link that, when clicked by a victim, would:\n- Steal user chat message history \n- Access all LLM interactions stored in the user\u0027s session.\n- Access connected MCP Servers \n- Interact with any MCP servers connected to the victim\u0027s session (public or authenticated/private), potentially allowing the attacker to perform actions on the victim\u0027s behalf\n\n### Mitigation:\n\n- PR: https://github.com/cloudflare/agents/pull/841\n- Agents-sdk users should upgrade to `agents@0.3.10`\n- Developers using `configureOAuthCallback` with custom error handling in their own applications should ensure all user-controlled input is escaped before interpolation.\n\n### Credits\n\nDisclosed responsibly by Nishant Kumawat",
  "id": "GHSA-w5cr-2qhr-jqc5",
  "modified": "2026-02-13T21:04:00Z",
  "published": "2026-02-13T21:04:00Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/cloudflare/agents/security/advisories/GHSA-w5cr-2qhr-jqc5"
    },
    {
      "type": "WEB",
      "url": "https://github.com/cloudflare/agents/pull/841"
    },
    {
      "type": "WEB",
      "url": "https://github.com/cloudflare/agents/commit/3f490d045844e4884db741afbb66ca1fe65d4093"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/cloudflare/agents"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Cloudflare Agents has a Reflected Cross-Site Scripting (XSS) vulnerability in AI Playground site"
}