Vulnerability · Published Oct 29, 2026 · Assigned by GitHub_M
CVE-2026-119285Fiber: CORS wildcard origins matched without a dot boundary, allowing credentialed cross-origin reads
Medium 5.9
In plain English
A medium-severity security flaw in fiber from gofiber. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 3% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Go | github.com/gofiber/fiber/v2 | 2.52.3 | GHSA-g5jq-qmqr-qrwf |
| Go | github.com/gofiber/fiber/v2 | 2.52.3 | GO-2026-6896 |
| Ubuntu:26.10 | golang-github-gofiber-fiber | no fix listed | UBUNTU-CVE-2026-119285 |
| Ubuntu:26.10 | golang-github-gofiber-fiber-v2 | no fix listed | UBUNTU-CVE-2026-119285 |
Affected products (as reported)
Weakness: CWE-346, CWE-942 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N
References
- https://github.com/gofiber/fiber/security/advisories/GHSA-g5jq-qmqr-qrwf x_refsource_CONFIRM
- https://github.com/gofiber/fiber/pull/2915 x_refsource_MISC
- https://github.com/gofiber/fiber/commit/1aac6f618b6bd3e159d2449acb4232a2170b976b x_refsource_MISC
- https://github.com/gofiber/fiber/releases/tag/v2.52.3 x_refsource_MISC