CVE-2025-66565
📋 TL;DR
A critical vulnerability in Fiber Utils library versions 2.0.0-rc.3 and below causes predictable UUID generation when the system's cryptographic random number generator fails, returning values like the zero UUID. This compromises security-critical operations in all Fiber applications using these functions. Attackers could exploit this to bypass authentication, authorization, or other security mechanisms.
💻 Affected Systems
- Fiber Utils (gofiber/utils)
📦 What is this software?
Utils by Gofiber
Utils by Gofiber
Utils by Gofiber
Utils by Gofiber
Utils by Gofiber
Utils by Gofiber
Utils by Gofiber
Utils by Gofiber
Utils by Gofiber
Utils by Gofiber
Utils by Gofiber
Utils by Gofiber
Utils by Gofiber
Utils by Gofiber
Utils by Gofiber
Utils by Gofiber
Utils by Gofiber
Utils by Gofiber
Utils by Gofiber
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise through authentication bypass, privilege escalation, or session hijacking using predictable UUIDs for security tokens, session IDs, or cryptographic operations.
Likely Case
Authentication bypass or session hijacking in applications using vulnerable UUID functions for security tokens, allowing unauthorized access to user accounts or administrative functions.
If Mitigated
Limited impact if applications have additional security layers, but still vulnerable to targeted attacks exploiting predictable UUIDs in specific contexts.
🎯 Exploit Status
Exploitation requires triggering crypto/rand.Read() failures, which could occur under specific system conditions or be induced by attackers in some environments.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.0.0-rc.4
Vendor Advisory: https://github.com/gofiber/utils/security/advisories/GHSA-m98w-cqp3-qcqr
Restart Required: Yes
Instructions:
1. Update go.mod to require github.com/gofiber/utils v2.0.0-rc.4 or later. 2. Run 'go mod tidy' to update dependencies. 3. Rebuild and redeploy all affected applications. 4. Restart services using the updated binaries.
🔧 Temporary Workarounds
Replace UUID functions with secure alternatives
allReplace calls to vulnerable Fiber Utils UUID functions with secure alternatives like github.com/google/uuid
go get github.com/google/uuid
Replace imports and function calls in code
🧯 If You Can't Patch
- Implement additional validation layers to reject zero UUIDs and other predictable values in security-critical contexts
- Monitor for crypto/rand failures and alert when they occur, as this indicates the vulnerability may be triggered
🔍 How to Verify
Check if Vulnerable:
Check go.mod or go.sum for github.com/gofiber/utils dependency with version <=2.0.0-rc.3Check Version:
grep 'github.com/gofiber/utils' go.modVerify Fix Applied:
Verify go.mod requires github.com/gofiber/utils v2.0.0-rc.4 or later and check that applications no longer use predictable UUIDs under test conditions📡 Detection & Monitoring
Log Indicators:
- Log entries showing crypto/rand failures
- Authentication attempts using zero UUID or other predictable values
- Unexpected successful authentications with suspicious patterns
Network Indicators:
- Unusual authentication patterns
- Multiple authentication attempts with sequential or predictable tokens
SIEM Query:
source="application_logs" AND ("crypto/rand" AND "fail" OR "error") OR ("uuid" AND "00000000-0000-0000-0000-000000000000")