CVE-2021-36776 is a high-severity security vulnerability in github.com/rancher/rancher (go), affecting versions >= 2.5.0, <= 2.5.9. It is fixed in 2.5.10.
Impact A flaw discovered in Rancher versions from 2.5.0 up to and including 2.5.9 allows an authenticated user to impersonate any user on a cluster through the Steve API proxy, without requiring knowledge of the impersonated user's credentials. This is due to the Steve API proxy not dropping the impersonation header before sending the request to the Kubernetes API. A malicious user with authenticated access to Rancher could use this to impersonate another user with administrator access in Rancher, receiving, then, administrator level access in the cluster. Patches Patched versions include releases 2.5.10, 2.6.0 and later versions. Workarounds Limit access in Rancher to trusted users. There is not a direct mitigation besides upgrading to the patched Rancher versions. For more information If you have any questions or comments about this advisory: Reach out to SUSE Rancher Security team for security related inquiries. Open an issue in Rancher repository. Verify our support matrix and product support lifecycle.
CVE-2021-36776 has a CVSS score of 8.8 (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 (2.5.10). Upgrading removes the vulnerable code path.
go
github.com/rancher/rancher (>= 2.5.0, <= 2.5.9)github.com/rancher/rancher → 2.5.10 (go)Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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Already deployed Kodem? See CVE-2021-36776 in your environment →Upgrade github.com/rancher/rancher to 2.5.10 or later to resolve this vulnerability.
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CVE-2021-36776 is a high-severity security vulnerability in github.com/rancher/rancher (go), affecting versions >= 2.5.0, <= 2.5.9. It is fixed in 2.5.10.
CVE-2021-36776 has a CVSS score of 8.8 (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.
github.com/rancher/rancher (go) versions >= 2.5.0, <= 2.5.9 is affected.
Yes. CVE-2021-36776 is fixed in 2.5.10. Upgrade to this version or later.
Whether CVE-2021-36776 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
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.
Upgrade github.com/rancher/rancher to 2.5.10 or later.