CVE-2020-36599 is a critical-severity (CVSS 9.8) CWE-116 vulnerability in omniauth. A fix is available for omniauth — see the affected versions and patch details below.
OmniAuth's `lib/omniauth/failure_endpoint.rb` does not escape `message_key` value
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
omniauth💎omniauthReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.
Description
lib/omniauth/failure_endpoint.rb in OmniAuth before 1.9.2 (and before 2.0) does not escape the message_key value.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | omniauth | all versions | 1.9.2bundle update omniauth --conservative |
| 💎RubyGems | omniauth | ≥ 2.0.0.pre.rc1&&< 2.0.0 | 2.0.0bundle update omniauth --conservative |
Affected Products
omniauthomniauthDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for omniauth, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update omniauth to 1.9.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-36599 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.
Frequently Asked Questions
Is CVE-2020-36599 in your dependencies?
Find it across RubyGems, including transitive dependencies.