CVE-2026-40302 zrok has reflected XSS in GitHub OAuth callback via unsanitized refreshInterval error rendering
Attackers can execute arbitrary JavaScript in the OAuth server origin via reflected XSS in the GitHub OAuth callback, potentially leading to account takeover.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-40302?
CVE-2026-40302 is a medium-severity cross-site scripting vulnerability in openziti zrok, published on 17 Apr 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
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.
Which versions are affected by CVE-2026-40302?
6 open source packages ship an affected version, including github.com/openziti/zrok and github.com/openziti/zrok/v2. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/openziti/zrok Go | All versions | None |
github.com/openziti/zrok Go | All versions to 1.1.11 | None |
github.com/openziti/zrok Go | All versions to 1.1.11 | None |
github.com/openziti/zrok/v2 Go | All versions | 2.0.1 |
github.com/openziti/zrok/v2 Go | All versions | 2.0.1 |
github.com/openziti/zrok/v2 Go | All versions | 2.0.1 |
Products include Netfoundry Zrok.
How do I fix CVE-2026-40302?
Upgrade to a fixed version.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-40302 being exploited?
There is no known exploitation of CVE-2026-40302 in the wild and no public exploit code.
Other vulnerabilities in openziti zrok
- CVE-2026-45568 zrok Python ProxyShare can be used as an SSRF proxy through absolute URL paths
- CVE-2026-42275 zrok: WebDAV drive backend follows symlinks outside DriveRoot, enabling host filesystem read/write
- CVE-2026-45576 zrok copy writes attacker-controlled WebDAV paths outside the destination root
- CVE-2026-40303 zrok allows unauthenticated DoS via unbounded memory allocation in striped session cookie parsing
- CVE-2026-40304 zrok's broken ownership check in DELETE /api/v2/unaccess allows non-admin to delete global frontend records
Sources
Also known as GHSA-4fxq-2x3x-6xqx, GO-2026-5118.