dbcve.org
ZrokApplication · Netfoundry

CVE-2026-40302

MEDIUM · 6.1 CVSS v3.1 Published 2026-04-17
Fix available
A fix is available. Upgrade to 2.0.1 or later.
See remediation →
68/100
Remediation priority · Elevated
Remotely reachable No privileges

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
zrok is software for sharing web services, files, and network resources. Prior to version 2.0.1, the proxyUi template engine uses Go's 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's origin. Version 2.0.1 patches the issue.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

zrok versions prior to 2.0.1 contain a reflected XSS vulnerability in the GitHub OAuth callback handlers. The refreshInterval query parameter is embedded unescaped into error messages rendered via Go's text/template (which performs no HTML escaping), allowing arbitrary JavaScript execution in the victim's browser after completing the OAuth flow.

MitigationUpgrade to zrok version 2.0.1 or later, which replaces text/template with html/template for proper HTML escaping of user-controlled input.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
ZrokApplication
Affected:< 2.0.1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed zrok version
    Run 'zrok --version' or check the binary version metadata
    Affected if Version is below 2.0.1 (e.g., 2.0.0, 1.x.x series)
  2. Determine if GitHub OAuth is configured
    Check zrok configuration files or environment for GitHub OAuth-related settings (client ID, secret, OAuth endpoints)
    Affected if GitHub OAuth is enabled and configured in the zrok environment
  3. Identify the OAuth callback endpoint
    Locate the OAuth callback handler code or trace the redirect URI used during GitHub OAuth flow
    Affected if The callback handler processes the refreshInterval query parameter without HTML escaping
  4. Inspect error message rendering
    Examine the code paths that render error messages during OAuth failures; look for usage of text/template instead of html/template
    Affected if Error messages are rendered using text/template with the refreshInterval parameter inserted directly

You are affected if zrok version is below 2.0.1 AND GitHub OAuth is configured, since the unescaped refreshInterval parameter can be injected into error pages.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 2.0.1 or later
Fixed in 2.0.1
Interim mitigation

Upgrade to zrok version 2.0.1 or later, which replaces text/template with html/template for proper HTML escaping of user-controlled input.

Recommended fix High confidence

2.0.1

  1. Check the current installed version of zrok using 'zrok --version' or your package manager
  2. Upgrade zrok to version 2.0.1 or later using your package manager or installation method (e.g., 'zrok update', 'brew upgrade', or reinstall from the official releases)
  3. Verify the upgrade was successful by checking 'zrok --version' shows 2.0.1 or higher
  4. If running a self-hosted instance, restart the zrok service to load the updated binary

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Zrok Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
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An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,088.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-40302 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data