CVE-2025-66565: gofiber utils · Unchecked Return Value
Affects gofiber utilsSource CVE Database V5
Not known to be exploited · CVSS 9.3 Critical · fixed in 2.0.0 : patch gofiber utils as a priority.
Data as of 26 Oct 2026, 09:15 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 40% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 2.0.0
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 9 Dec 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Gogithub.com/gofiber/utilspkg:golang/github.com/gofiber/utilsOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
European organizations should immediately upgrade all gofiber utils dependencies to version 2.0.0-rc.4 or later to ensure the vulnerability is patched. Conduct a thorough code audit to identify all uses of UUID generation in security-critical contexts and verify that no fallback to predictable UUIDs occurs. Implement additional runtime checks to detect failures in crypto/rand and log such events for early warning. Where feasible, replace UUID-based security tokens with cryptographically secure random values generated by well-maintained libraries. Employ defense-in-depth by enforcing strict session management, multi-factor authentication, and anomaly detection to mitigate potential exploitation. Regularly monitor Fiber framework and gofiber utils releases for further security updates. Educate developers on proper error handling and secure random number generation best practices to prevent similar issues.
Description
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.