CVE-2020-5415
CRITICALCVE-2020-5415 is a critical-severity (CVSS 10) CWE-290 vulnerability in github.com/concourse/concourse. O3 Security confirms whether CVE-2020-5415 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
GitLab auth uses full name instead of username as user ID, allowing impersonation
Real-World Exposure
github.com/concourse/concourse🐹github.com/concourse/concourse🐹github.com/concourse/dex🐹github.com/concourse/dex🐹github.com/concourse/dex🐹github.com/concourse/concourse🐹github.com/concourse/concourseReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Concourse, versions prior to 6.3.1 and 6.4.1, in installations which use the GitLab auth connector, is vulnerable to identity spoofing by way of configuring a GitLab account with the same full name as another user who is granted access to a Concourse team. GitLab groups do not have this vulnerability, so GitLab users may be moved into groups which are then configured in the Concourse team.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/concourse/concourse | ≥ 6.4.0&&< 6.4.1 | 6.4.1 |
| 🐹Go | github.com/concourse/concourse | ≥ 1.6.1&&< 6.3.1 | 6.3.1 |
| 🐹Go | github.com/concourse/dex | ≥ 6.4.0&&< 6.4.1 | 6.4.1 |
| 🐹Go | github.com/concourse/dex | ≥ 0.0.0&&< 6.3.1 | 6.3.1 |
| 🐹Go | github.com/concourse/dex | all versions | 0.0.0-20200730150203-821b48abfd88 |
| 🐹Go | github.com/concourse/concourse | all versions | 0.0.0-20200730151558-b00d1c8d8576 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/concourse/concourse. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/concourse/concourse to 6.4.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-5415 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2020-5415 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2020-5415. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2020-5415 in your dependencies?
O3 detects CVE-2020-5415 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.