Live › vulnerability › CVE-2026-119285
Fiber's CORS middleware matches wildcard subdomain origins by host suffix without requiring a dot boundary, so an attacker-controlled domain ending in the configured base domain is reflected as allowed. When credentials are enabled, a logged-in user visiting that domain lets the attacker's page read authenticated cross-origin responses.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-29 22:27 UTC. All times on this page are UTC.
Applications built with Fiber that use the CORS middleware with a wildcard-subdomain AllowOrigins value and AllowCredentials enabled are exposed. Apps without wildcard origins or without credentials enabled, and apps not using the affected version range, can skip it.
No product ranges from the sources yet.
go.mod; affected versions are from 2.52.1 up to but not including 2.52.3.cors.New and AllowOrigins using a wildcard subdomain value such as https://*.example.com.AllowCredentials is set to true in the same CORS configuration.2.52.3.Each row is the first time that source carried this signal. The analyst’s rows are its own findings.
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.
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