Fiber has an insecure fallback in utils.UUIDv4() / utils.UUID() — predictable / zero‑UUID on crypto/rand failure

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

9.2 · 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 · score source

EPSS

• CVE-2025-66630: 0.53% estimated exploitation activity in the next 30 days; percentile 45.19 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Fiber v2 contains an internal vendored copy of gofiber/utils, and its functions UUIDv4() and UUID() inherit the same critical weakness described in the upstream advisory. On Go versions prior to 1.24, the underlying crypto/rand implementation can return an error if secure randomness cannot be obtained. In such cases, these Fiber v2 UUID functions silently fall back to generating predictable values — the all-zero UUID 00000000-0000-0000-0000-000000000000. On Go 1.24+, the language guarantees that crypto/rand no longer returns an error (it will block or panic instead), so this vulnerability primarily affects Fiber v2 users running Go 1.23 or earlier, which Fiber v2 officially supports. 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,…

Published by the source

9 Feb 2026, 15:28 UTC

Last modified by the source

9 Feb 2026, 18:49 UTC

Source last checked

26 Oct 2026, 15:14 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-68rr-p4fp-j59v

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# Patch Next advisory brief: CVE-2025-66630

Advisory: Fiber has an insecure fallback in utils.UUIDv4() / utils.UUID() — predictable / zero‑UUID on crypto/rand failure
IDs: CVE-2025-66630, GHSA-68rr-p4fp-j59v
Record: https://patchnext.com/advisories/cve-2025-66630 (revision 1, source checked 26 Oct 2026, 15:14 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.2)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/gofiber/fiber/v2 2.52.11. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/gofiber/fiber/v2: affected < 2.52.11; fixed in 2.52.11

## Suggested inspection (read-only)
- Go github.com/gofiber/fiber/v2: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/gofiber/fiber/v2.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-68rr-p4fp-j59v (GitHub-reviewed advisory GHSA-68rr-p4fp-j59v lists affected ranges: Go github.com/gofiber/fiber/v2 >=0 <2.52.11)

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