CyberSecBulletin
CVE-2022-24817NVD status: Modified

flux2: Improper Control of Generation of Code

Published Updated By the CyberSecBulletin desk

CVE-2022-24817 is a critical-severity improper control of generation of code vulnerability in flux2 from Fluxcd, with a CVSS 3.1 base score of 9.9 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 flux2 versions: flux2 < v0.29.0 >= v0.1.0; helm-controller < v0.23.0 >= v0.1.0; kustomize-controller < v0.19.0 >= v0.2.0. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1.12% chance of exploitation within 30 days, higher than 67% of scored CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Update Helm-controller to 0.19.0 or a later version.
  2. Update Kustomize-controller to 0.23.0 or a later version.
  3. Read the advisory on github.com for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
Fluxcdflux2flux2 < v0.29.0 >= v0.1.0; helm-controller < v0.23.0 >= v0.1.0; kustomize-controller < v0.19.0 >= v0.2.0Not stated
FluxcdHelm-controller0.2.0 up to, but not including, 0.19.00.19.0
FluxcdKustomize-controller0.1.0 up to, but not including, 0.23.00.23.0

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
ChangedThe attack can reach beyond the vulnerable component into other systems.
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:C/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.19.9CriticalCNA (github.com)
CVSS 3.19.9CriticalNVD
CVSS 2.06.5MediumNVD

Official description

Flux2 is an open and extensible continuous delivery solution for Kubernetes. Flux2 versions between 0.1.0 and 0.29.0, helm-controller 0.1.0 to v0.19.0, and kustomize-controller 0.1.0 to v0.23.0 are vulnerable to Code Injection via malicious Kubeconfig. In multi-tenancy deployments this can also lead to privilege escalation if the controller's service account has elevated permissions. Workarounds include disabling functionality via Validating Admission webhooks by restricting users from setting the `spec.kubeConfig` field in Flux `Kustomization` and `HelmRelease` objects. Additional mitigations include applying restrictive AppArmor and SELinux profiles on the controller’s pod to limit what binaries can be executed. This vulnerability is fixed in kustomize-controller v0.23.0 and helm-controller v0.19.0, both included in flux2 v0.29.0

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

The underlying weakness: Improper Control of Generation of Code

The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.

How developers prevent this class of flaw

  • Refactor your program so that you do not have to dynamically generate code.
  • Run your code in a jail or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which code can be executed by your product. Examples include the Unix chroot jail and AppArmor. In general, managed code may provide some protection. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of your application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails.
  • Use dynamic tools and techniques that interact with the product using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The product's operation may slow down, but it should not become unstable, crash, or generate incorrect results.

More Improper Control of Generation of Code vulnerabilities (CWE-94)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in flux2

All flux2 vulnerabilities

Recent Improper Control of Generation of Code vulnerabilities

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