CVE-2021-36783: Rancher doesn't properly sanitize credentials in cluster template answers

Should you act?

Critical, preconditions apply

Severe if exploited, but exploitation needs conditions that may not apply to you. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 0.8%, percentile 55: FIRST’s model estimates a 0.8% chance of exploitation activity in the next 30 days, higher than 55% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Needs an account (low (any account)). Exposure depends on who can log in.
• Only applies if your dependency tree includes github.com/rancher/rancher (Go) >= 2.5.0, <= 2.5.12, fixed in 2.5.13; github.com/rancher/rancher (Go) >= 2.6.0, <= 2.6.3, fixed in 2.6.4. Check your lockfile, including transitive dependencies.

What it is

A Insufficiently Protected Credentials vulnerability in SUSE Rancher allows authenticated Cluster Owners, Cluster Members, Project Owners and Project Members to read credentials, passwords and API tokens that have been stored in cleartext and exposed via API endpoints. This issue affects: SUSE Rancher Rancher versions prior to 2.6.4; Rancher versions prior to 2.5.13.

From the GitHub advisory

Impact

It was discovered that in Rancher versions up to and including 2.5.12 and 2.6.3 there is a failure to properly sanitize credentials in cluster template answers. This failure can lead to plaintext storage and exposure of credentials, passwords and API tokens.

The exposed credentials are visible in Rancher to authenticated Cluster Owners, Cluster Members, Project Owners and Project Members on the endpoints /v1/management.cattle.io.clusters, /v3/clusters and /k8s/clusters/local/apis/management.cattle.io/v3/clusters.

Sensitive fields are now stripped from Clusters objects before the object is stored. For objects that existed before this security fix, a one-time migration happens on startup.

Important: - It is highly advised to review for potential leaked credentials in this scenario, and to change them if deemed necessary. - The final impact severity for confidentiality, integrity and availability is dependent on the permissions that the leaked credentials have on their own services.

Weakness type: CWE-522, CWE-200, CWE-312.

Product: github.com/rancher/rancher (Go) · Assigned by: suse · Published: 2022-09-07

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: low (any account)
• User interaction: none
• Scope: changed (can affect other components)

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• FIRST EPSS (model of 2026-10-21): 0.78% probability of exploitation activity in the next 30 days; percentile 55.

Timeline

• 2022-09-07 — CVE record published by suse
• 2024-09-16 — CVE record last updated
• 2026-03-03 — GitHub-reviewed advisory GHSA-8w87-58w6-hfv8 published (critical)

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-8w87-58w6-hfv8 github.com
2. CVE.org record CVE-2021-36783 cve.org
3. NVD entry CVE-2021-36783 nvd.nist.gov

Other references from the CVE record and advisory

1. bugzilla.suse.com bugzilla.suse.com
2. github.com github.com

Critical Go advisories · Today’s Security Digest