CVE-2021-36778: Github.com/rancher/rancher Remote Code Execution Vulnerability

HIGH
Advisory Identifier: GHSA-4fc7-hc63-7fjg
CVSS 8.3
CWE-522 CWE-200 CWE-863
Published
Advisory Summary

CVE-2021-36778 is a HIGH (CVSS 8.3) remote code execution vulnerability (CWE-522: Insufficiently Protected Credentials) affecting Github.com/rancher/rancher libraries in the Go ecosystem. The issue involves exposure of repository credentials to external third-party sources in rancher. Remediation is available by upgrading affected packages to version 2.6.3, 2.5.12.

CVE-2021-36778 at a Glance

CVE Identifier CVE-2021-36778
GHSA Identifier GHSA-4fc7-hc63-7fjg
Severity HIGH
CVSS v3.1 Base Score 8.3
CWE Classification CWE-522: Insufficiently Protected Credentials
Affected Product Github.com/rancher/rancher
Package Ecosystem Go
Published Date
Last Updated

Security Impact

CVSS: 8.3

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability Low (A:L)

How to Fix CVE-2021-36778

To remediate this vulnerability, upgrade all affected Github.com/rancher/rancher dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

github.com/rancher/rancher fixed: 2.6.3
Upgrade github.com/rancher/rancher to 2.6.3
github.com/rancher/rancher fixed: 2.5.12
Upgrade github.com/rancher/rancher to 2.5.12
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release:

inspect dependencies for github.com/rancher/rancher

How to Check if You Are Affected

To determine whether your application is affected by CVE-2021-36778, inspect your project dependencies for Github.com/rancher/rancher:

inspect dependencies for github.com/rancher/rancher

Analyze the terminal output to locate any version of Github.com/rancher/rancher in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.6.3), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-522: Insufficiently Protected Credentials, where the product transmits or stores authentication credentials, but it uses an insecure method that is susceptible to unauthorized interception and/or retrieval. In Github.com/rancher/rancher, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact This issue only happens when the user configures access credentials to a private repository in Rancher inside `Apps & Marketplace > Repositories`. It affects Rancher versions 2.5.0 up to and including 2.5.11 and from 2.6.0 up to and including 2.6.2. An insufficient check of the same-origin policy when downloading Helm charts from a configured private repository can lead to exposure of the repository credentials to a third-party provider. This exposure happens when the private repository: 1. Does an HTTP redirect to a third-party repository or external storage provider. 2. Downloads an icon resource for the chart hosted on a third-party provider. The address of the private repository is not leaked, only the credentials are leaked in the HTTP `Authorization` header in base64 format. With the patched versions, the default behavior now is to only send the private repository credentials when subdomain or domain hostname match when following the redirect or downloading external resources. ### Patches Patched versions include releases 2.5.12, 2.6.3 and later versions. ### Workarounds 1. Update Rancher to a patched version. 2. Check the Helm charts in your configured private repository for possible redirects to third-party storage, and for Helm chart icons from third-party sources. 3. Evaluate any Helm chart that might lead to the mentioned scenario and change affected credentials if deemed necessary. ### References Information about the same-origin check and how to disable it is available in Rancher [documentation](https://rancher.com/docs/rancher/v2.6/en/helm-charts/#repositories). ### For more information If you have any questions or comments about this advisory: * Reach out to [SUSE Rancher Security team](https://github.com/rancher/rancher/security/policy) for security related inquiries. * Open an issue in [Rancher](https://github.com/rancher/rancher/issues/new/choose) repository. * Verify our [support matrix](https://www.suse.com/suse-rancher/support-matrix/all-supported-versions/) and [product support lifecycle](https://www.suse.com/lifecycle/).

CVE-2021-36778 Affected Github.com/rancher/rancher Versions

2 component(s)
Fixed Versions:
2.6.32.5.12
Product / Package Ecosystem Affected Versions Fixed Version
github.com/rancher/rancher
Go
≥ 2.6.0
< 2.6.3
2.6.3
github.com/rancher/rancher
Go
≥ 2.5.0
< 2.5.12
2.5.12

References

Frequently Asked Questions

What is CVE-2021-36778?
CVE-2021-36778 is a security vulnerability in Github.com/rancher/rancher involving Exposure of repository credentials to external third-party sources in Rancher under CWE-522: Insufficiently Protected Credentials.
Which Github.com/rancher/rancher versions are affected?
Affected versions include releases prior to 2.6.3, 2.5.12 across affected packages: github.com/rancher/rancher.
What version fixes CVE-2021-36778?
Upgrading to 2.6.3, 2.5.12 (or the latest patched release for your respective branch) resolves the vulnerability.
Is github.com/rancher/rancher affected?
Yes, github.com/rancher/rancher is affected in releases prior to 2.6.3, 2.5.12. Upgrade your dependency to 2.6.3, 2.5.12 or later.
What is the CVSS score of CVE-2021-36778?
CVE-2021-36778 has a CVSS v3.1 base score of 8.3 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L.
What CWE is associated with CVE-2021-36778?
CVE-2021-36778 is classified under CWE-522: Insufficiently Protected Credentials (The product transmits or stores authentication credentials, but it uses an insecure method that is susceptible to unauthorized interception and/or retrieval.).
How can I check Go dependencies for CVE-2021-36778?
Run the dependency tree command: 'inspect dependencies for github.com/rancher/rancher'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-4fc7-hc63-7fjg",
  "modified" : "2022-05-02T19:33:34Z",
  "published" : "2022-05-02T19:33:34Z",
  "aliases" : [ "CVE-2021-36778" ],
  "summary" : "Exposure of repository credentials to external third-party sources in Rancher",
  "details" : "### Impact\nThis issue only happens when the user configures access credentials to a private repository in Rancher inside `Apps & Marketplace > Repositories`. It affects Rancher versions 2.5.0 up to and including 2.5.11 and from 2.6.0 up to and including 2.6.2.\n\nAn insufficient check of the same-origin policy when downloading Helm charts from a configured private repository can lead to exposure of the repository credentials to a third-party provider. This exposure happens when the private repository:\n\n1. Does an HTTP redirect to a third-party repository or external storage provider.\n2. Downloads an icon resource for the chart hosted on a third-party provider.\n\nThe address of the private repository is not leaked, only the credentials are leaked in the HTTP `Authorization` header in base64 format.\n\nWith the patched versions, the default behavior now is to only send the private repository credentials when subdomain or domain hostname match when following the redirect or downloading external resources.\n\n### Patches\nPatched versions include releases 2.5.12, 2.6.3 and later versions.\n\n### Workarounds\n1. Update Rancher to a patched version.\n2. Check the Helm charts in your configured private repository for possible redirects to third-party storage, and for Helm chart icons from third-party sources.\n3. Evaluate any Helm chart that might lead to the mentioned scenario and change affected credentials if deemed necessary.\n\n### References\nInformation about the same-origin check and how to disable it is available in Rancher [documentation](https://rancher.com/docs/rancher/v2.6/en/helm-charts/#repositories).\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Reach out to [SUSE Rancher Security team](https://github.com/rancher/rancher/security/policy) for security related inquiries.\n* Open an issue in [Rancher](https://github.com/rancher/rancher/issues/new/choose) repository.\n* Verify our [support matrix](https://www.suse.com/suse-rancher/support-matrix/all-supported-versions/) and [product support lifecycle](https://www.suse.com/lifecycle/).",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/rancher/rancher"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.6.0"
      }, {
        "fixed" : "2.6.3"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/rancher/rancher"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.5.0"
      }, {
        "fixed" : "2.5.12"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/rancher/rancher/security/advisories/GHSA-4fc7-hc63-7fjg"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-36778"
  }, {
    "type" : "WEB",
    "url" : "https://bugzilla.suse.com/show_bug.cgi?id=1191466"
  }, {
    "type" : "PACKAGE",
    "url" : "github.com/rancher/rancher"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-200", "CWE-522", "CWE-863" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2022-05-02T19:33:34Z",
    "nvd_published_at" : "2022-05-02T12:16:00Z"
  }
}