CVE-2025-66565

high-risk

Published 2025-12-09

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.

Do I need to act?

0.09% chance of exploitation

EPSS score — low exploit probability

Not on CISA KEV list

No confirmed active exploitation reported to CISA

Patch status unknown

Check vendor advisories for fix availability and mitigation guidance

CVSS 9.8/10 Critical

NETWORK / LOW complexity

Affected Products (19)

Utils

Affected Vendors

Gofiber

References (3)

Patch https://github.com/gofiber/utils/commit/6c6cf047032b9c8dff43d29f990b4b10e9b02d47

Vendor Advisory https://github.com/gofiber/utils/security/advisories/GHSA-m98w-cqp3-qcqr

/ 100

high-risk

Severity 32/34 · Critical

Exploitability 0/34 · Minimal

Exposure 19/34 · Moderate