CVE-2025-66565
CRITICALDescription
Fiber Utils is a collection of common functions created for Fiber. In versions 2.0.0-rc.3 and below, when the system's cryptographic random number generator (crypto/rand) fails, both functions silently fall back to returning predictable UUID values, including the zero UUID "00000000-0000-0000-0000-000000000000". The vulnerability occurs through two related but distinct failure paths, both ultimately caused by crypto/rand.Read() failures, compromising the security of all Fiber applications using these functions for security-critical operations. This issue is fixed in version 2.0.0-rc.4.
How to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Exploit Intelligence
Low risk: more likely to be exploited than 38% of all known CVEs.
References
Related Vulnerabilities
Other CWE-252 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2005-4360 | High | 7.8 | 87% | - | - |
| CVE-2007-3798 | Critical | 9.8 | 70% | - | Fix |
| CVE-2010-0211 | Critical | 9.8 | 28% | - | Fix |
| CVE-2022-23626 | High | 8.5 | 9.9% | - | Fix |
| CVE-2019-10902 | High | 7.5 | 4.0% | - | - |
| CVE-2018-20216 | High | 7.5 | 3.9% | - | Fix |
Common questions
How do I fix CVE-2025-66565?
No published fix for CVE-2025-66565 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
Is CVE-2025-66565 being actively exploited?
Not that we know of. CVE-2025-66565 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.46% is the estimated probability that it will be exploited in the next 30 days. That is higher than 38% of all scored CVEs.
How severe is CVE-2025-66565?
CVE-2025-66565 has a CVSS v3 base score of 9.8, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-12-11.