CVE-2021-25737 is a vulnerability in Kubernetes
Published on September 6, 2021
Holes in EndpointSlice Validation Enable Host Network Hijack
A security issue was discovered in Kubernetes where a user may be able to redirect pod traffic to private networks on a Node. Kubernetes already prevents creation of Endpoint IPs in the localhost or link-local range, but the same validation was not performed on EndpointSlice IPs.
Vulnerability Analysis
CVE-2021-25737 can be exploited with network access, and requires user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality, a small impact on integrity and availability.
Weakness Type
What is a Denylist / Deny List Vulnerability?
The product implements a protection mechanism that relies on a list of inputs (or properties of inputs) that are not allowed by policy or otherwise require other action to neutralize before additional processing takes place, but the list is incomplete, leading to resultant weaknesses. Developers often try to protect their products against malicious input by performing tests against inputs that are known to be bad, such as special characters that can invoke new commands. However, such lists often only account for the most well-known bad inputs. Attackers may be able to find other malicious inputs that were not expected by the developer, allowing them to bypass the intended protection mechanism.
CVE-2021-25737 has been classified to as a Denylist / Deny List vulnerability or weakness.
Products Associated with CVE-2021-25737
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Affected Versions
Kubernetes:- Version unspecified, <= 1.18.18 is affected.
- Version unspecified, <= 1.19.10 is affected.
- Version unspecified, <= 1.20.6 is affected.
- Version unspecified, <= 1.21.0 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.