CVE-2025-66630

Critical

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.

SeverityCritical
CVSS9.4
Exploit probability—
ProductFiber
PublishedFeb 9, 2026
First seenFeb 9, 2026
Weakness typeCWE-338CWE-338

How to fix

Update
  • gofiber fiber2.52.11 or later
  • github.com/gofiber/fiber/v22.52.11 or later

Affected products

ProductAffected versionsFixed in
gofiber fiberv < 2.52.112.52.11
github.com/gofiber/fiber/v2Gov < 2.52.112.52.11
github.com/gofiber/fiberGoNo range specified—

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