flux2: Allocation of Resources Without Limits or Throttling
CVE-2022-36049 is a high-severity allocation of resources without limits or throttling vulnerability in flux2 from Fluxcd, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected flux2 versions: >= 0.0.4, < 0.23.0; >= 0.0.17, < 0.32.0. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1.54% chance of exploitation within 30 days, higher than 75% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Helm to 3.9.4 or a later version.
- Update Helm-controller to 0.23.0 or a later version.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Fluxcd | flux2 | >= 0.0.4, < 0.23.0; >= 0.0.17, < 0.32.0 | Not stated |
| Helm | Helm | 3.0.0 up to, but not including, 3.9.4 | 3.9.4 |
| Fluxcd | Helm-controller | 0.0.4 up to, but not including, 0.23.0 | 0.23.0 |
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
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.7 | High | CNA (github.com) |
| CVSS 3.1 | 7.5 | High | NVD |
Official description
Flux2 is a tool for keeping Kubernetes clusters in sync with sources of configuration, and Flux's helm-controller is a Kubernetes operator that allows one to declaratively manage Helm chart releases. Helm controller is tightly integrated with the Helm SDK. A vulnerability found in the Helm SDK that affects flux2 v0.0.17 until v0.32.0 and helm-controller v0.0.4 until v0.23.0 allows for specific data inputs to cause high memory consumption. In some platforms, this could cause the controller to panic and stop processing reconciliations. In a shared cluster multi-tenancy environment, a tenant could create a HelmRelease that makes the controller panic, denying all other tenants from their Helm releases being reconciled. Patches are available in flux2 v0.32.0 and helm-controller v0.23.0.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Allocation of Resources Without Limits or Throttling
The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.
How developers prevent this class of flaw
- Clearly specify the minimum and maximum expectations for capabilities, and dictate which behaviors are acceptable when resource allocation reaches limits.
- Limit the amount of resources that are accessible to unprivileged users. Set per-user limits for resources. Allow the system administrator to define these limits. Be careful to avoid CWE-410.
- For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
More Allocation of Resources Without Limits or Throttling vulnerabilities (CWE-770)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
- github.com/fluxcd/flux2/security/advisories/GHSA-p2g7-xwvr-rrw3Third Party Advisory
- github.com/helm/helm/security/advisories/GHSA-7hfp-qfw3-5jxhThird Party Advisory
Third-party and government advisories
- bugs.chromium.org/p/oss-fuzz/issues/detail?id=44996Mailing List, Third Party Advisory
- bugs.chromium.org/p/oss-fuzz/issues/detail?id=48360Mailing List, Third Party Advisory
Other vulnerabilities in flux2
- 7.8 High severity
- 8.8 High severity
- 9.9 Critical severity
Recent Allocation of Resources Without Limits or Throttling vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
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