CVE-2021-31999High· 8.8▾ TwilightRancher Privilege escalation vulnerability via malicious "Connection" header
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 48.4 · likelihood 0.2 · exploitation 0
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Exploit-prediction probability, daily snapshots since Jul 10.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via OSV
Last analysed / modified upstream
1.1%
A vulnerability was discovered in Rancher 2.0.0 through the aforementioned patched versions, where a malicious Rancher user could craft an API request directed at the proxy for the Kubernetes API of a managed cluster to gain access to information they do not have access to. This is done by passing the "Impersonate-User" or "Impersonate-Group" header in the Connection header, which is then correctly removed by the proxy. At this point, instead of impersonating the user and their permissions, the request will act as if it was from the Rancher management server and incorrectly return the information. The vulnerability is limited to valid Rancher users with some level of permissions on the cluster. There is not a direct mitigation besides upgrading to the patched Rancher versions.
github.com/rancher/rancher >= 2.0.0, < 2.4.16github.com/rancher/rancher >= 2.5.0, < 2.5.9Upgrade to a patched release:
github.com/rancher/rancher 2.4.16github.com/rancher/rancher 2.5.9Connected by shared product, vendor, weakness, or advisory.
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