GHSA-vrph-m5jj-c46c CVE-2022-21951

Rancher's weave CNI password is not configured when a cluster is created from an RKE template

Medium Go

Severity: 6.8 / 10; Medium · CVSS 3.1
Exploit chance (EPSS): 0.39%; Chance of exploitation in the next 30 days. Higher than 33.64% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: CWE-311 Missing Encryption of Sensitive Data; CWE-319 Cleartext Transmission of Sensitive Information
Fix: 2.6.5; Upgrade github.com/rancher/rancher to this version or later

Description

Impact

This vulnerability only affects customers using Weave CNI (Container Network Interface) when configured through RKE templates.

A flaw was discovered in Rancher versions from 2.5.0 up to and including 2.5.13 and from 2.6.0 up to and including 2.6.4, where a UI (user interface) issue with RKE templates does not include a value for the Weave password when Weave is chosen as the CNI.

If a cluster is created based on the mentioned template and Weave is configured as the CNI, no password will be created for network encryption in Weave, therefore network traffic in the cluster will be sent unencrypted.

This issue does not happen when a cluster, with Weave configured as CNI, is created without using an RKE template.

The impact of this vulnerability is higher when nodes on the cluster are on different locations and communicate with one another through the Internet, where monitoring (sniffing) of the network traffic by third-party entities can be more easily achieved.

Patches

Patched versions include releases 2.5.14, 2.6.5 and later versions of Rancher. Besides upgrading to a Rancher patched version, the workarounds listed below must be applied in order for Weave to properly encrypt the network traffic.

Workarounds

A manual password can be set in Weave by directly editing Weave's DaemonSet on the affected cluster to add the WEAVE_PASSWORD environment variable together with the a value for the password.

$ kubectl -n kube-system edit ds weave-net

<snipped>
      containers:
      - command:
        - /home/weave/launch.sh
        env:
        - name: INIT_CONTAINER
          value: "true"
        - name: HOSTNAME
          valueFrom:
            fieldRef:
              apiVersion: v1
              fieldPath: spec.nodeName
        - name: IPALLOC_RANGE
          value: <IP allocation range>
        - name: WEAVE_PASSWORD
          value: "insert strong secret password here"
        image: <Weave image>
<snipped>

A new RKE template revision must be created in order to properly generate the Weave password on new clusters.

Notes

In order to provide protection against brute-force attacks, that might break the network encryption, a strong password must be generated for the workaround. Weave's documentation provides recommendations for generating a strong password.
Manually generating the password for the workaround is only needed on affected versions of Rancher. This step is not needed when creating new RKE templates on patched versions of Rancher.

For more information

If you have any questions or comments about this advisory:

Reach out to SUSE Rancher Security team for security related inquiries.
Open an issue in Rancher repository.
Verify SUSE Rancher support matrix and product support lifecycle.

Affected versions

Go

Package	Vulnerable	Fixed in
github.com/rancher/rancher	`>= 2.6.0, < 2.6.5`	`2.6.5`
github.com/rancher/rancher	`>= 2.5.0, < 2.5.14`	`2.5.14`

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

github.com/rancher/rancher Go → `2.6.5`

go

go get github.com/rancher/rancher@v2.6.5 && go mod tidy

Severity breakdown

CVSS 3.1 6.8

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N

Attack vector: Network
Attack complexity: High
Privileges required: Low
User interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: None

Weakness

CWE-311: Missing Encryption of Sensitive Data

The product does not encrypt sensitive or critical information before storage or transmission.

How to prevent it

Requirements: Clearly specify which data or resources are valuable enough that they should be protected by encryption. Require that any transmission or storage of this data/resource should use well-vetted encryption algorithms.
Architecture and Design: Ensure that encryption is properly integrated into the system design, including but not necessarily limited to: Encryption that is needed to store or transmit private data of the users of the system Encryption that is needed to protect the system itself from unauthorized disclosure or tampering Identify the separate needs and contexts for encryption: One-way (i.e., only the user or recipient needs to have the key). This can be achieved using public key cryptography, or other techniques in which the encrypting party (i.e., the product) does not need to have access to a private key. Two-way (i.e., the encryption can be automatically performed on behalf of a user, but the key must be available so that the plaintext can be automatically recoverable by that user). This requires storage of the private key in a format that is recoverable only by the user (or perhaps by the operating system) in a way that cannot be recovered by others. Using threat modeling or other techniques, assume that data can be compromised through a separate vulnerability or weakness, and determine where encryption will be most effective. Ensure that data that should be private is not being inadvertently exposed using weaknesses such as insecure permissions (CWE-732). [REF-7]
Architecture and Design: When there is a need to store or transmit sensitive data, use strong, up-to-date cryptographic algorithms to encrypt that data. Select a well-vetted algorithm that is currently considered to be strong by experts in the field, and use well-tested implementations. As with all cryptographic mechanisms, the source code should be available for analysis. For example, US government systems require FIPS 140-2 certification. Do not develop custom or private cryptographic algorithms. They will likely be exposed to attacks that are well-understood by cryptographers. Reverse engineering techniques are mature. If the algorithm can be compromised if attackers find out how it works, then it is especially weak. Periodically ensure that the cryptography has not become obsolete. Some older algorithms, once thought to require a billion years of computing time, can now be broken in days or hours. This includes MD4, MD5, SHA1, DES, and other algorithms that were once regarded as strong. [REF-267]
Architecture and Design: Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
Implementation, Architecture and Design: When using industry-approved techniques, use them correctly. Don't cut corners by skipping resource-intensive steps (CWE-325). These steps are often essential for preventing common attacks.
Implementation: Use naming conventions and strong types to make it easier to spot when sensitive data is being used. When creating structures, objects, or other complex entities, separate the sensitive and non-sensitive data as much as possible.

CWE-319: Cleartext Transmission of Sensitive Information

The product transmits sensitive or security-critical data in cleartext in a communication channel that can be sniffed by unauthorized actors.

How to prevent it

Architecture and Design: Before transmitting, encrypt the data using reliable, confidentiality-protecting cryptographic protocols.
Implementation: When using web applications with SSL, use SSL for the entire session from login to logout, not just for the initial login page.
Implementation: When designing hardware platforms, ensure that approved encryption algorithms (such as those recommended by NIST) protect paths from security critical data to trusted user applications.
Testing: Use tools and techniques that require manual (human) analysis, such as penetration testing, threat modeling, and interactive tools that allow the tester to record and modify an active session. These may be more effective than strictly automated techniques. This is especially the case with weaknesses that are related to design and business rules.
Operation: Configure servers to use encrypted channels for communication, which may include SSL or other secure protocols.

References

Advisories

nvd.nist.gov/vuln/detail/CVE-2022-21951

Packages

github.com/rancher/rancher

Timeline

May 25, 2022 Published
Jul 8, 2026 Last updated by the source
Nov 1, 2026 Latest EPSS score

Advisory	Severity	Why it's related
GHSA-4j6x-2764-m8gh Rancher has over-inclusive team membership expansion in GitHub App authentication provider	High	Also affects github.com/rancher/rancher
GHSA-vx8h-4prv-g744 Rancher has Privilege Escalation from Project Owner to Host	High	Also affects github.com/rancher/rancher
GHSA-mhc6-2gfq-xx62 Rancher vulnerable to command injection through unsanitized YAML parameter	Critical	Also affects github.com/rancher/rancher
GHSA-5v3h-x4wf-5c35 Rancher Extensions have arbitrary file access via path traversal	High	Also affects github.com/rancher/rancher
GHSA-gqf8-rvrh-g7w6 Rancher cloud credentials can be used through proxy API by users without access	Critical	Also affects github.com/rancher/rancher
GHSA-hwm2-4ph6-w6m5 Rancher's restricted PodSecurityPolicy does not prevent containers from running as a privileged user	High	Also affects github.com/rancher/rancher
GHSA-mc24-7m59-4q5p Rancher CLI skips TLS verification on Rancher CLI login command	Medium	Also affects github.com/rancher/rancher
GHSA-mw39-9qc2-f7mg Rancher exposes sensitive information through audit logs	Medium	Also affects github.com/rancher/rancher

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