CVE-2021-32574: Hashicorp Consul Missing SSL Certificate Validation
Summary
CVE-2021-32574: Hashicorp Consul Missing SSL Certificate Validation. Affects github.com/hashicorp/consul versions < 1.10.1. Fixed in 1.10.1. How to fix ↓
Also tracked for
The same CVE-2021-32574 is tracked separately for each ecosystem and vendor. Its fix information is the same; the package and affected versions differ.
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Background
HashiCorp Consul is a Go-based tool used for service discovery, configuration, and orchestration. It provides a distributed system for service mesh architectures. Consul allows organizations to automate network configurations, service discovery, and health checking. It is widely used in cloud-native environments to manage and monitor services. However, a vulnerability has been identified in Consul versions prior to 1.10.1 (including Consul Enterprise) that results in missing SSL certificate validation. This vulnerability affects the security of communication between Consul and upstream services.
Vulnerability Detail
The vulnerability, identified as CVE-2021-32574, arises from the lack of validation of the Subject Alternative Name (SAN) of an upstream in Consul's xds component. This means that Consul does not ensure that the SAN of an upstream is properly validated, potentially allowing an attacker to perform man-in-the-middle attacks or intercept sensitive information transmitted between Consul and upstream services. The severity of this vulnerability is rated as HIGH with a CVSS score of 7.5.
How To Fix
Latest published version: v1.22.7 as of 22 Oct 2026
go get github.com/hashicorp/consul@v1.22.7Upgrading to it may include breaking changes; the version below is the minimum fixed release for this vulnerability.
If you need the minimum change
1.10.1
This is the first release that contains the fix.
go get github.com/hashicorp/consul@v1.10.1Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, users can manually validate the SSL certificate of the upstream services by inspecting the certificate's Subject Alternative Name (SAN) and ensuring it matches the expected value. This can be done using various tools and libraries available for SSL certificate validation. Here is an example of how to perform SSL certificate validation using the OpenSSL command-line tool:
$ openssl s_client -connect <upstream_host>:<upstream_port> -servername <upstream_host>
This command will establish a connection to the upstream service and display the SSL certificate information, including the SAN. Users should verify that the SAN matches the expected value before proceeding.
Conclusion
In conclusion, the HashiCorp Consul Missing SSL Certificate Validation vulnerability (CVE-2021-32574) poses a significant risk to the security of communication between Consul and upstream services. It is crucial to upgrade to Consul version 1.10.1 or later to ensure proper SSL certificate validation and protect against potential man-in-the-middle attacks. For further support and assistance with vulnerability remediation, please contact DevNack.com.
See every vulnerability recorded for github.com/hashicorp/consul →
FAQ
This vulnerability can potentially allow an attacker to intercept sensitive information transmitted between Consul and upstream services. It may also enable man-in-the-middle attacks, compromising the confidentiality and integrity of the communication.
Consul versions prior to 1.10.1, including Consul Enterprise, are affected by this vulnerability.
You can use the Vulert Playground at Vulert Scanner to check if your application is affected by this vulnerability. Simply provide your Gopkg.lock file, and Vulert will analyze it to identify any open-source vulnerabilities, including CVE-2021-32574.
Yes, a fix is available in Consul version 1.10.1. It is recommended to upgrade to this version or later to mitigate the vulnerability.
As a temporary workaround, users can manually validate the SSL certificate of the upstream services by inspecting the certificate's Subject Alternative Name (SAN) and ensuring it matches the expected value. However, upgrading to Consul version 1.10.1 or later is the recommended solution.
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