Skip to content
Fencer Vulns
medium 5.9

CVE-2026-119285 json

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

published 2026-10-29 10 d ago modified 2026-11-05 3 d ago also GHSA-g5jq-qmqr-qrwf , GO-2026-6896 , EUVD-2026-113402

cvss
5.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 2%
public exploits
0
none known

Summary

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.

Patch / fix

  • go github.com/gofiber/fiber/v2 2.52.3

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-119285 updated cvss 5.9

github.com/gofiber/fiber: Fiber: Information disclosure via improper CORS origin validation

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
5 d ago

Exploit prediction

0.13% chance of exploitation in the next 30 days, higher than 2% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/gofiber/fiber/security/advisories/GHSA-g5jq-qmqr-qrwf referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N
GitHub 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N

Affected packages

ecosystem package affected fixed in
go github.com/gofiber/fiber/v2
>=2.52.1, <2.52.3
2.52.3

Affected products

  • gofiber fiber

Classification

Weakness
  • CWE-346 Origin Validation Error
  • CWE-942 Permissive Cross-domain Security Policy with Untrusted Domains

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.