Vulnerability · Published Feb 9, 2026 · Assigned by GitHub_M

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

Critical 9.2

In plain English

A critical-severity security flaw in fiber from gofiber. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 45% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)9.2Critical

Exploit odds (30 days)0.5%top 55.2% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Go	github.com/gofiber/fiber	no fix listed	GO-2026-4471
Go	github.com/gofiber/fiber/v2	2.52.11	GHSA-68rr-p4fp-j59v
Go	github.com/gofiber/fiber/v2	2.52.11	GO-2026-4471

Affected products (as reported)

Vendor	Product	Versions
gofiber	fiber	< 2.52.11

Weakness: CWE-338 · 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

References

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