CVE-2025-66565

Fiber Utils UUIDv4 and UUID Silent Fallback to Predictable Values

State: Published
Severity: 9.3 Critical
Published: Dec 9, 2025
Updated: Dec 9, 2025
Reserved: Dec 4, 2025

Description

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.

Scores

CVSS	Score	Vector	Source
4.0	9.3 Critical	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	GitHub_M

Weaknesses

CWE-252 Unchecked Return Value
CWE-331 Insufficient Entropy
CWE-338 Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)

Affected Products

Product	Versions
utilsgofiber	github.com/gofiber/utils <= 1.2.0Affected github.com/gofiber/utils/v2 < 2.0.0-rc.4Affected

References

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