CVE-2025-66565

9.3 CRITICAL 0.5% exploit odds Fix listed Other

What it is

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.

At a glance

Exploitability: Can be exploited over the network without logging in. High risk of data exposure, data tampering.
Exploit odds: 0.5% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2025-12-09 16:18 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-10-07 20:10 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.5% in the next 30 days (EPSS).
Severity: 9.3 CRITICAL (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2025-12-09 16:18 UTC
Last modified: 2026-10-07 20:10 UTC
Exploit probability: 0.5% · EPSS, next 30 days
Weakness: CWE-252
Record status: Analyzed

Affected

Gofiber Utils ≤ 1.2.0
Gofiber Utils 2.0.0

Attack profile CVSS 4.0 · 9.3

Attack vector: Network
Complexity: Low
Attack requirements: None
Privileges needed: None
User interaction: None
Confidentiality: High
Integrity: High
Availability: Low

Raw vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2025-66565.md and follow it. Check whether this project is affected by CVE-2025-66565. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

· More options · Status badge

Download Square Reddit

Fix and advisories

References

NVD record · CVE.org record