CVE-2018-20744 — v2
MEDIUMCVE-2018-20744 is a medium-severity (CVSS 5.9) CWE-346 vulnerability in github.com/gofiber/fiber/v2. A fix is available for github.com/gofiber/fiber/v2 — see the affected versions and patch details below.
github.com/gofiber/fiber/v2 vulnerable to Origin Validation Error
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2018-20744 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,166 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/gofiber/fiber/v2🐹github.com/rs/corsReal-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
The Olivier Poitrey Go CORS handler through 1.3.0 actively converts a wildcard CORS policy into reflecting an arbitrary Origin header value, which is incompatible with the CORS security design, and could lead to CORS misconfiguration security problems.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/gofiber/fiber/v2 | ≥ 2.0.0&&< 2.43.0 | 2.43.0go get github.com/gofiber/fiber/v2@v2.43.0 |
| 🐹Go | github.com/rs/cors | all versions | 1.5.0go get github.com/rs/cors@v1.5.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/gofiber/fiber/v2, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/gofiber/fiber/v2 to 2.43.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2018-20744 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2018-20744 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2018-20744. 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-2018-20744 in your dependencies?
O3 Security finds CVE-2018-20744 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.