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MEDIUM severity

CVE-2018-20744 — fiber

MEDIUMFix: gofiber/fiber#2339

CVE-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

Also known asGHSA-927h-x4qj-r242GO-2023-1792
Published
Updated
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed
Exploitation data as of Nov 2, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
0.7%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs54th percentile — riskier than 54% of all scored CVEsHighest risk
0.00%0.41%0.81%1.22%0.1%0.7%May 26Sep 26Nov 26

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

2 pkgs affected
🐹github.com/gofiber/fiber/v2🐹github.com/rs/cors

Real-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

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
🐹Gogithub.com/gofiber/fiber/v2≥ 2.0.0&&< 2.43.02.43.0go get github.com/gofiber/fiber/v2@v2.43.0
🐹Gogithub.com/rs/corsall versions1.5.0go get github.com/rs/cors@v1.5.0

Affected Products

1 product · 1 configurations
Application
go corsgo_cors_project
≤ 1.3.0
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    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.

  2. 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.

  3. 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

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.
O3 Security · Impact-Aware SCA

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CVE-2018-20744: fiber — Fixed in 2.43.0