Home/CVE/A security issue was discovered in Kubernetes where a user may be able to redirect pod traffic to private networks on a
CVE

CVE-2021-25737

A security issue was discovered in Kubernetes where a user may be able to redirect pod traffic to private networks on a

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.

LOW · CVSS 2.7 EPSS 0.00379
Monitor
  • No active-exploitation, high-EPSS, or public-exploit signals - routine patching cadence
Sigma rules8 YARA rules0
⬡

Weakness Classification

CWE-184Incomplete List of Disallowed Inputs
CWE-601URL Redirection to Untrusted Site ('Open Redirect')
▤

Affected Products & Versions

4
kubernetes>= 1.16.0 and < 1.18.19
kubernetes>= 1.19.0 and < 1.19.10
kubernetes>= 1.20.0 and < 1.20.7
kubernetesall versions
▤

Affected Packages

1
Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
Go k8s.io/kubernetes MODERATE fixed in 1.18.19
◈

Sigma Hunt Rules

8
Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.
productmediumKubernetes Events Deleted
productmediumKubernetes Admission Controller Modification
productmediumKubernetes CronJob/Job Modification
productmediumKubernetes Potential Enumeration Activity
productmediumKubernetes Secrets Modified or Deleted
productmediumKubernetes Rolebinding Modification
▣

Scoring & Timeline

2.7
LOW · CVSS v3.1 · jordan@liggitt.net
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD06 Sep 2021 · 12:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N
⚑

Vendor Advisories

2
suse-csafopenSUSE-SU-2025:15424-1
rhsaRHSA-2021:2437Moderate
🔗

References & Sources

3
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://github.com/kubernetes/kubernetes/issues/102106PatchThird Party Advisory
https://groups.google.com/g/kubernetes-security-announce/c/xAiN3924thYMailing ListThird Party Advisory
https://security.netapp.com/advisory/ntap-20211004-0004/Third Party Advisory
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