CVE-2026-119285 · GHSA-g5jq-qmqr-qrwf

Fiber: CORS wildcard origins matched without a dot boundary, allowing credentialed cross-origin reads

Risk score: 45/100
CVSS: 5.9 v3.1
Published: 29 Oct 2026

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What to know

What it is: Fiber is an Express inspired web framework written in Go. From 2.52.1 until 2.52.3, the CORS middleware's validateDomain wildcard matcher in middleware/cors/utils.go strips the scheme and checks only a host suffix without requiring a dot boundary. An application configured with a wildcard-subdomain AllowOrigins value …
Affected: github.com/gofiber/fiber/v2 (go) >= 2.52.1, <= 2.52.2
Fix: Upgrade github.com/gofiber/fiber/v2 to 2.52.3 or later.
Exploitation: Public proof of concept

Why it is Yellow

CVSS 5.9 medium
Public exploit or proof of concept referenced
On your watchlist: Go

Affected packages

Package	Ecosystem	Vulnerable	Fixed in
github.com/gofiber/fiber/v2	go	>= 2.52.1, <= 2.52.2	2.52.3

References

Original description

Fiber is an Express inspired web framework written in Go. From 2.52.1 until 2.52.3, the CORS middleware's validateDomain wildcard matcher in middleware/cors/utils.go strips the scheme and checks only a host suffix without requiring a dot boundary. An application configured with a wildcard-subdomain AllowOrigins value and AllowCredentials enabled can reflect an unrelated attacker-controlled origin whose host merely ends with the configured base domain. A user who visits that origin can expose authenticated cross-origin responses to the attacker's page; empty-label origins and later comma-space parsing hardening are outside this advisory. This issue is fixed in version 2.52.3.

Last activity 30 Oct 2026. Patch Forecast updates every hour.