{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "zrok is software for sharing web services, files, and network resources. Prior to version 2.0.1, the proxyUi template engine uses Go\u0027s text/template (which performs no HTML escaping) instead of html/template. The GitHub OAuth callback handlers in both publicProxy and dynamicProxy embed the attacker-controlled refreshInterval query parameter verbatim into an error message when time.ParseDuration fails, and render that error unescaped into HTML. An attacker can deliver a crafted login URL to a victim; after the victim completes the GitHub OAuth flow, the callback page executes arbitrary JavaScript in the OAuth server\u0027s origin. Version 2.0.1 patches the issue."
    }
  ],
  "id": "CVE-2026-40302",
  "lastModified": "2026-04-17T21:16:34.997",
  "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": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-04-17T21:16:34.997",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/openziti/zrok/releases/tag/v2.0.1"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/openziti/zrok/security/advisories/GHSA-4fxq-2x3x-6xqx"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-79"
        },
        {
          "lang": "en",
          "value": "CWE-116"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Primary"
    }
  ]
}

{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/openziti/zrok"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "1.1.11"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/openziti/zrok/v2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.0.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-40302"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-116",
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-16T21:08:55Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "**Summary**\nThe proxyUi template engine uses Go\u0027s text/template (which performs no HTML escaping) instead of html/template. The GitHub OAuth callback handlers in both publicProxy and dynamicProxy embed the attacker-controlled refreshInterval query parameter verbatim into an error message when time.ParseDuration fails, and render that error unescaped into HTML. An attacker can deliver a crafted login URL to a victim; after the victim completes the GitHub OAuth flow, the callback page executes arbitrary JavaScript in the OAuth server\u0027s origin.\n\n- Attack Vector: Network \u2014 the attack is delivered as a crafted URL over the internet.\n- Attack Complexity: Low \u2014 no race conditions or special environment prerequisites.\n- Privileges Required: None \u2014 the attacker needs no account on the zrok instance.\n- User Interaction: Required \u2014 the victim must click the crafted link and complete the GitHub OAuth flow.\n- Scope: Changed \u2014 the injected script executes in the OAuth server\u0027s origin, not the victim\u0027s share origin.\n- Confidentiality Impact: Low \u2014 the script runs in the OAuth server origin after a failed flow; no session cookie is set at this point, limiting what can be exfiltrated to what is visible in the DOM and what can be requested from the OAuth server.\n- Integrity Impact: Low \u2014 the script can initiate new OAuth flows or submit forms on behalf of the victim in the OAuth server origin.\n- Availability Impact: None.\n\n**Affected Components**\n\n- endpoints/proxyUi/template.go \u2014 init() / WriteTemplate (lines 8, 18, 99) \u2014 text/template used for HTML rendering\n- endpoints/proxyUi/template.html \u2014 line 119 \u2014 {{ .Error }} in HTML without escaping\n- endpoints/publicProxy/providerGithub.go \u2014 login callback closure (lines 93, 128, 130)\n- endpoints/dynamicProxy/providerGithub.go \u2014 loginHandler() (lines 110, 146, 148)",
  "id": "GHSA-4fxq-2x3x-6xqx",
  "modified": "2026-04-16T21:08:55Z",
  "published": "2026-04-16T21:08:55Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/openziti/zrok/security/advisories/GHSA-4fxq-2x3x-6xqx"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/openziti/zrok"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "zrok: Reflected XSS in GitHub OAuth callback via unsanitized refreshInterval error rendering"
}