CyberSecBulletin
CVE-2023-3676NVD status: Modified

A security issue was discovered in Kubernetes where a user that can create pods on Windows…

Published Updated By the CyberSecBulletin desk

CVE-2023-3676 is a high-severity improper input validation vulnerability in kubelet from Kubernetes, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. Affected kubelet versions: v1.28.0; v1.27.0 through v1.27.4; v1.26.0 through v1.26.7, and others listed below. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 13.2% chance of exploitation within 30 days, which is in the top 3.57% of all scored CVEs.

Patch this week

EPSS places it among the vulnerabilities most likely to be exploited soon.

What to do

  1. Update Kubernetes to 1.24.17 or 1.25.13 or 1.26.8 or 1.27.5, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
Kuberneteskubeletv1.28.0; v1.27.0 through v1.27.4; v1.26.0 through v1.26.7; v1.25.0 through v1.25.12; v1.24.16 and earlierNot stated
KubernetesKubernetesbefore 1.24.17; 1.25.0 up to, but not including, 1.25.13; 1.26.0 up to, but not including, 1.26.8; 1.27.0 up to, but not including, 1.27.5; 1.28.0 up to, but not including, 1.28.11.24.17, 1.25.13, 1.26.8, 1.27.5, 1.28.1

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.18.8HighCNA (liggitt.net)
CVSS 3.18.8HighNVD

Official description

A security issue was discovered in Kubernetes where a user that can create pods on Windows nodes may be able to escalate to admin privileges on those nodes. Kubernetes clusters are only affected if they include Windows nodes.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Input Validation

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

How developers prevent this class of flaw

  • Consider using language-theoretic security (LangSec) techniques that characterize inputs using a formal language and build recognizers for that language. This effectively requires parsing to be a distinct layer that effectively enforces a boundary between raw input and internal data representations, instead of allowing parser code to be scattered throughout the program, where it could be subject to errors or inconsistencies that create weaknesses.
  • Use an input validation framework such as Struts or the OWASP ESAPI Validation API. Note that using a framework does not automatically address all input validation problems; be mindful of weaknesses that could arise from misusing the framework itself (CWE-1173).
  • Understand all the potential areas where untrusted inputs can enter the product, including but not limited to: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls.

More Improper Input Validation vulnerabilities (CWE-20)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Patches and release notes

Third-party and government advisories

Other vulnerabilities in kubelet

All kubelet vulnerabilities

Recent Improper Input Validation vulnerabilities

Spotted an error? Tell us.