Kube-Proxy Windows Traffic Forwarding Bug (CVE-2021-25736)
CVE-2021-25736 Published on October 30, 2023
Windows kube-proxy LoadBalancer contention
Kube-proxy
on Windows can unintentionally forward traffic to local processes
listening on the same port (spec.ports[*].port) as a LoadBalancer
Service when the LoadBalancer controller
does not set the status.loadBalancer.ingress[].ip field. Clusters
where the LoadBalancer controller sets the
status.loadBalancer.ingress[].ip field are unaffected.
Vulnerability Analysis
CVE-2021-25736 is exploitable with network access, and requires user privileges. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to have a high impact on confidentiality, with no impact on integrity and availability.
Weakness Type
Process Control
Executing commands or loading libraries from an untrusted source or in an untrusted environment can cause an application to execute malicious commands (and payloads) on behalf of an attacker. Process control vulnerabilities take two forms: 1. An attacker can change the command that the program executes: the attacker explicitly controls what the command is. 2. An attacker can change the environment in which the command executes: the attacker implicitly controls what the command means. Process control vulnerabilities of the first type occur when either data enters the application from an untrusted source and the data is used as part of a string representing a command that is executed by the application. By executing the command, the application gives an attacker a privilege or capability that the attacker would not otherwise have.
Products Associated with CVE-2021-25736
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Affected Versions
Kubernetes:- Before and including v1.20.5 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.