What’s Vulnerable › Vulnerabilities

CVE-2020-5409: Concourse Open Redirect in the /sky/login endpoint

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.9% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-05-14 · updated 2026-06-17
• Weakness: CWE-601

Description

Pivotal Concourse, most versions prior to 6.0.0, allows redirects to untrusted websites in its login flow. A remote unauthenticated attacker could convince a user to click on a link using the OAuth redirect link with an untrusted website and gain access to that user's access token in Concourse. (This issue is similar to, but distinct from, CVE-2018-15798.)

Affected products

• Pivotal Concourse: before 5.2.8; from 5.3.0 before 5.5.10; from 5.6.0 before 5.8.1 — fixed in 5.2.8, 5.5.10, 5.8.1

How to fix

Upgrade to a fixed version: Pivotal Concourse 5.2.8, 5.5.10, 5.8.1. Check the vendor advisory for mitigations.

References

• https://tanzu.vmware.com/security/cve-2020-5409
• https://tanzu.vmware.com/security/cve-2020-5409

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