Vulnerability · Published Dec 9, 2025 · Assigned by GitHub_M
CVE-2025-66565Fiber Utils UUIDv4 and UUID Silent Fallback to Predictable Values
Critical 9.3
In plain English
A critical-severity security flaw in utils from gofiber. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 41% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Go | github.com/gofiber/utils | 1.2.0 | GHSA-m98w-cqp3-qcqr |
| Go | github.com/gofiber/utils | 1.2.0 | GO-2025-4208 |
| Go | github.com/gofiber/utils/v2 | 2.0.0-rc.4 | GHSA-m98w-cqp3-qcqr |
| Go | github.com/gofiber/utils/v2 | 2.0.0-rc.4 | GO-2025-4208 |
Affected products (as reported)
Weakness: CWE-252, CWE-331, CWE-338 · 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