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CVE Record

CVE-2021-3499: A vulnerability was found in OVN Kubernetes in versions up to and including 0.3.0 where the Egress Firewall...

A vulnerability was found in OVN Kubernetes in versions up to and including 0.3.0 where the Egress Firewall does not reliably apply firewall rules when there is multiple DNS rules. It could lead to potentially lose of confidentiality, integrity or availability of a service.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

This issue can cause OVN Kubernetes egress firewall rules to be applied unreliably when multiple DNS rules are configured. In business terms, traffic that teams expected to block or restrict may not be consistently controlled, affecting confidentiality, integrity, or availability depending on what those rules protect.

Executive priority

Treat this as a targeted infrastructure exposure review rather than an emergency based on current evidence. Prioritize production clusters where egress firewall rules are a control for sensitive systems, because unreliable enforcement can undermine security assumptions.

Technical view

CVE-2021-3499 affects openshift/ovn-kubernetes versions up to and including 0.3.0. The egress firewall does not reliably enforce firewall rules when multiple DNS rules are present. The CVE maps this to CWE-863, indicating an authorization or access-control enforcement weakness.

Likely exposure

Exposure is most likely in OpenShift or Kubernetes environments using affected ovn-kubernetes versions with egress firewall policies containing multiple DNS rules. Clusters without OVN Kubernetes, without egress firewall use, or without multiple DNS rules are less likely to match the described condition.

Exploitation context

The provided sources do not show active exploitation, public exploit tooling, or inclusion in CISA KEV. The business risk depends on whether affected egress rules protect sensitive services, regulated data paths, or critical operational dependencies.

Researcher notes

The public bundle is sparse: no CVSS vector, no named fixed version, and only a high-level behavior description. Analysis should focus on affected version confirmation, policy shape, and vendor advisory follow-up rather than exploit reproduction.

Mitigation direction

  • Inventory ovn-kubernetes versions across relevant Kubernetes or OpenShift clusters.
  • Review Red Hat or vendor guidance for fixed builds, supported backports, or configuration mitigations.
  • Identify policies using multiple DNS-based egress firewall rules.
  • Use compensating network controls for critical egress restrictions where feasible.
  • Prioritize remediation where egress policy protects sensitive services or data paths.

Validation and detection

  • Confirm whether ovn-kubernetes is deployed and record its version.
  • Review egress firewall policies for multiple DNS rules.
  • Check whether affected rules protect sensitive destinations or production services.
  • Verify vendor advisory status before declaring a version remediated.
  • Document clusters where the described configuration is absent.
Prepared
Confidence
medium
Sources
3

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · medium confidence lookup

CWE-863: Authorization and privilege behavior lookup

Authorization weaknesses can support privilege escalation and valid-account review, depending on exploit path. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
description · low confidence lookup

Container behavior lookup

The affected technology mentions containers, so container-specific ATT&CK technique review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2021-3499 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
2Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/aopenshift/ovn-kubernetesAll ovn-kubernetes versions up to and including 0.3.0Listed
Weakness

CWE details

CWE-863

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.