CVE-2021-36778

Exposure of repository credentials to external third-party sources in Rancher

This issue only happens when the user configures access credentials to a private repository in Rancher inside Apps & Marketplace > Repositories. It affects Rancher versions 2.5.0 up to and including 2.5.11 and from 2.6.0 up to and including 2.6.2.

An insufficient check of the same-origin policy when downloading Helm charts from a configured private repository can lead to exposure of the repository credentials to a third-party provider. This exposure happens when the private repository:

1. Does an HTTP redirect to a third-party repository or external storage provider.
2. Downloads an icon resource for the chart hosted on a third-party provider.

The address of the private repository is not leaked, only the credentials are leaked in the HTTP Authorization header in base64 format.

With the patched versions, the default behavior now is to only send the private repository credentials when subdomain or domain hostname match when following the redirect or downloading external resources.

The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions. Typical impact: unauthorized data access or execution of privileged operations.

CVE-2021-36778 has a CVSS score of 8.3 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.6.3, 2.5.12); upgrading removes the vulnerable code path.

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Patched versions include releases 2.5.12, 2.6.3 and later versions.

1. What is CVE-2021-36778? CVE-2021-36778 is a high-severity incorrect authorization vulnerability in github.com/rancher/rancher (go), affecting versions >= 2.6.0, < 2.6.3. It is fixed in 2.6.3, 2.5.12. The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions.
2. How severe is CVE-2021-36778? CVE-2021-36778 has a CVSS score of 8.3 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of github.com/rancher/rancher are affected by CVE-2021-36778? github.com/rancher/rancher (go) versions >= 2.6.0, < 2.6.3 is affected.
4. Is there a fix for CVE-2021-36778? Yes. CVE-2021-36778 is fixed in 2.6.3, 2.5.12. Upgrade to this version or later.
5. Is CVE-2021-36778 exploitable, and should I be worried? Whether CVE-2021-36778 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2021-36778 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2021-36778?
   • Upgrade github.com/rancher/rancher to 2.6.3 or later
   • Upgrade github.com/rancher/rancher to 2.5.12 or later

Other vulnerabilities in github.com/rancher/rancher