Security readout for executives and security teams
Plain-English summary
Some Consul access-control rules could fail open instead of blocking traffic. In affected versions, a specific default-deny setup with one application-aware deny intention may still allow lower-level network traffic, weakening service-to-service isolation.
Executive priority
Treat as a targeted but important service-mesh control bypass. Prioritize remediation where Consul enforces segmentation for sensitive services, regulated workloads, or production east-west traffic.
Technical view
CVE-2021-36213 affects HashiCorp Consul and Consul Enterprise 1.9.0 through 1.10.0. A default deny policy combined with a single L7 application-aware intention deny action cancels out, causing the intention to fail open and allow L4 traffic. HashiCorp fixed it in 1.9.8 and 1.10.1.
Likely exposure
Exposure is most likely in Consul service mesh deployments using default deny intentions and L7 application-aware deny rules on affected versions. The bundle does not identify other affected products or configurations.
Exploitation context
The source bundle does not cite active exploitation, and the CVE is not marked KEV. The issue is still operationally meaningful because it can silently weaken intended service segmentation.
Researcher notes
Evidence is concise but consistent: the CVE description and HashiCorp advisory identify the fail-open condition and fixed versions. No CVSS, CWE, or public exploitation evidence is provided in the bundle.
Mitigation direction
- Upgrade Consul or Consul Enterprise to 1.9.8, 1.10.1, or later supported releases.
- Review HashiCorp HCSEC-2021-16 guidance for configuration-specific recommendations.
- For Gentoo-managed systems, apply the relevant GLSA-202208-09 updates.
- Review default deny and L7 intention policies for unintended fail-open behavior.
Validation and detection
- Inventory Consul and Consul Enterprise versions across clusters.
- Identify deployments running versions 1.9.0 through 1.10.0.
- Check for default deny policies with a single L7 deny intention.
- Confirm patched clusters enforce intended service-to-service deny behavior.
- Document any affected policy paths and remediation owners.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
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.
CVE-2021-36213 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
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.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://www.hashicorp.com/blog/category/consulCVE reference · x_refsource_MISC
- https://github.com/hashicorp/consul/releases/tag/v1.10.1CVE reference · x_refsource_CONFIRM
- https://discuss.hashicorp.com/t/hcsec-2021-16-consul-s-application-aware-intentions-deny-action-fails-open-when-combined-with-default-deny-policy/26855CVE reference · x_refsource_CONFIRM
- GLSA-202208-09CVE reference · vendor-advisory, x_refsource_GENTOO
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.