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

Status: published. Published: 2026-10-29. Updated: 2026-11-04.

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.

## Remediation

- fix: github.com/gofiber/fiber/v2 (Go): OSV reports a fixed version 2.52.3. Check the advisory for supported release branches. (source: OSV GHSA-g5jq-qmqr-qrwf) — https://github.com/advisories/GHSA-g5jq-qmqr-qrwf

## Affected products and versions

- gofiber / fiber: >= 2.52.1, < 2.52.3 (affected). Source: CNA: GitHub_M
-  / github.com/gofiber/fiber/v2 (github.com/gofiber/fiber/v2): ≥ 2.52.1; < 2.52.3 (affected, semver); OSV events: introduced 2.52.1; fixed 2.52.3. Source: OSV GHSA-g5jq-qmqr-qrwf

## Severity and prioritization

- CVSS 3.1: 5.9 (medium); CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: 0.13% as of 2026-11-03; percentile 2.53%

- SSVC: exploitation poc; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-346, CWE-942

## Exploit evidence

- exploit: https://github.com/gofiber/fiber/security/advisories/GHSA-g5jq-qmqr-qrwf (ADP: CISA-ADP)

## References

- https://github.com/gofiber/fiber/security/advisories/GHSA-g5jq-qmqr-qrwf (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/gofiber/fiber/pull/2915 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/gofiber/fiber/commit/1aac6f618b6bd3e159d2449acb4232a2170b976b (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/gofiber/fiber/releases/tag/v2.52.3 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/gofiber/fiber/security/advisories/GHSA-g5jq-qmqr-qrwf (ADP: CISA-ADP; exploit)

- https://github.com/advisories/GHSA-g5jq-qmqr-qrwf (OSV / GitHub Security Advisories; advisory)

- https://osv.dev/vulnerability/GHSA-g5jq-qmqr-qrwf (OSV / GitHub Security Advisories; osv)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-119285; retrieved 2026-11-04; source updated 2026-11-04

- OSV / GitHub Security Advisories: https://osv.dev/vulnerability/GHSA-g5jq-qmqr-qrwf; retrieved 2026-11-04; source updated 2026-10-30

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-119285; retrieved 2026-11-04; source updated Not reported

Revision: ce13f62e28c175d127714c06acfe996dd6ffd0c288a2ec8c721621f8125a659b

Canonical: https://y2.dev/cve/CVE-2026-119285

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