---
id: CVE-2025-66565
title: Fiber Utils is a collection of common functions created for Fiber
summary: >-
  Fiber Utils is a collection of common functions created for Fiber. In versions
  2.0.0-rc.3 and below, when the system's cryptographic random number generator
  (crypto/rand) fails, both functions silently fall back to returning
  predictable …
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-252
  - CWE-331
  - CWE-338
  - CWE-252
  - CWE-338
vendor: gofiber
product: utils
affected:
  - utils <= 1.2.0
  - utils = 2.0.0
published: '2025-12-09'
updated: '2026-10-07'
sourceUpdated: '2026-10-07T20:10:01.970'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-66565'
references:
  - url: >-
      https://github.com/gofiber/utils/commit/6c6cf047032b9c8dff43d29f990b4b10e9b02d47
    label: security-advisories@github.com
  - url: 'https://github.com/gofiber/utils/security/advisories/GHSA-m98w-cqp3-qcqr'
    label: security-advisories@github.com
  - url: 'https://github.com/gofiber/utils/security/advisories/GHSA-m98w-cqp3-qcqr'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
epss: 0.00468
epssPercentile: 0.38431
ingestedAt: '2026-10-07T20:46:46.828Z'
---

## Overview

Fiber Utils is a collection of common functions created for Fiber. In versions 2.0.0-rc.3 and below, when the system's cryptographic random number generator (crypto/rand) fails, both functions silently fall back to returning predictable UUID values, including the zero UUID "00000000-0000-0000-0000-000000000000". The vulnerability occurs through two related but distinct failure paths, both ultimately caused by crypto/rand.Read() failures, compromising the security of all Fiber applications using these functions for security-critical operations. This issue is fixed in version 2.0.0-rc.4.

## Affected

- `utils <= 1.2.0`
- `utils = 2.0.0`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.