CVE-2021-25737
Description
A security issue was discovered in Kubernetes where an authorized user may be able to redirect traffic to private networks on a Node. An untrusted user could exploit this by creating or modifying EndpointSlices to point to localhost or link-local addresses.
Statement
OpenShift Container Platform (OCP) 3.11 is not affected by this vulnerability as it does not support EndpointSlices. All current versions of OCP 4 support EndpointSlices and are therefore affected.
Mitigation
* Prevent untrusted users from creating or modifying EndpointSlices
* Creating a validating admission webhook that prevents EndpointSlices with endpoint addresses in the 127.0.0.0/8 and 169.254.0.0/16 ranges
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 2.7 | 4.8 | 2.7 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | Low | Low | Low |
| Privileges Required | High | High | High |
| User Interaction | None | Required | None |
| Scope | Unchanged | Changed | Unchanged |
| Confidentiality | Low | Low | Low |
| Integrity Impact | None | Low | None |
| Availability Impact | None | None | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N
NVD: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory)
An attacker could provide unexpected values and cause a program crash or arbitrary control of resource allocation, leading to excessive consumption of resources such as memory and CPU.
Confidentiality
Technical Impact: Read Memory; Read Files or Directories
An attacker could read confidential data if they are able to control resource references.
Integrity,Confidentiality,Availability
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
An attacker could use malicious input to modify data or possibly alter control flow in unexpected ways, including arbitrary command execution.
Acknowledgements
Red Hat would like to thank the Kubernetes Product Security Committee for reporting this issue. Upstream acknowledges John Howard (Google) as the original reporter.
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