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VulnerabilityPublished

CVE-2025-66630: gofiber fiber · PRNG

Affects gofiber fiberSource CVE Database V5

0

Not known to be exploited · CVSS 9.2 Critical : upgrade to 2.52.11 as a priority.

Data as of 26 Oct 2026, 12:55 UTC

CVSS 4.0 base score
9.2Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.5% chance of exploitation in 30 days – higher than 44% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 2.52.11
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

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 9 Feb 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade gofiber fiber to 2.52.11.

Affected software

ProductAffectedFixed in
gofiberfiberAffected
  • <2.52.11
Fixed in
  • 2.52.11

AI-suggested

European organizations should immediately upgrade all GoFiber dependencies to version 2.52.11 or later to ensure the vulnerability is patched. Additionally, they should verify that their Go runtime environment is version 1.24 or newer, as earlier versions have the underlying crypto/rand issue. Application developers must audit their code and middleware usage to confirm that UUID generation is secure and that no fallback to weak randomness occurs. Implementing runtime monitoring for unusual session or token reuse patterns can help detect exploitation attempts. Security teams should also review and strengthen session management, CSRF protections, and rate limiting configurations to reduce reliance on UUIDs alone. Where possible, consider integrating additional entropy sources or alternative secure random number generators. Finally, conduct penetration testing focused on session fixation and CSRF bypass scenarios to validate mitigations.

Description

CVE-2025-66630 is a critical vulnerability in the GoFiber web framework versions prior to 2.52.11, caused by the use of a cryptographically weak pseudo-random number generator (PRNG) in UUID generation. The issue arises because the underlying crypto/rand package in Go versions before 1.24 can return errors when secure randomness is unavailable, but Fiber's UUID functions do not propagate these errors. This leads to predictable or low-entropy UUIDs being used in security-sensitive middleware components such as sessions, CSRF protection, rate limiting, and request ID generation. Exploitation could allow attackers to predict identifiers, potentially bypassing security controls or causing session fixation. The vulnerability has a CVSS 4.0 score of 9.2 (critical) and is fixed in Fiber version 2.

References

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