CVE-2025-66565: Fiber Utils is a collection of common functions created for Fiber

Q: How do I fix CVE-2025-66565?

utils: upgrade to newer than 1.2.0. Exact commands for each OS are on this page.

Q: Is CVE-2025-66565 being exploited?

CVE-2025-66565 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2025-66565 affect?

CVE-2025-66565 affects utils. Severity is critical (CVSS 9.8). 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 UUI

Q: How urgent is CVE-2025-66565?

Priority 49/100. Critical severity; Remotely exploitable, no login, no user action

This month

CRITICAL 9.8REMOTEUPGRADE

CVE-2025-66565 is a critical-severity flaw (CVSS 9.8) affecting utils. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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, compromi

Why this priority

Critical severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 60%)
CISA exploited list	No
Weakness	CWE-252, CWE-331, CWE-338
Published	2025-12-09
Last modified	2026-10-07

Publisher (CNA): GitHub, Inc. · Vendor: gofiber

Last updated 2026-10-07 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2025-12-09 16:18 UTCPublished CVE record published
2026-10-07 20:10 UTCUpdated Record last modified

gofiber utils UPGRADE

Affected: <= 1.2.0 · 2.0.0 beta1 · 2.0.0 beta10 · 2.0.0 beta11 · 2.0.0 beta12 · 2.0.0 beta13 · 2.0.0 beta14 · 2.0.0 beta2

Fixed in: newer than 1.2.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy utils || rpm -q utils || utils --version

2. UPGRADE to newer than 1.2.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade utils

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade utils

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2025-66565?

utils: upgrade to newer than 1.2.0. Exact commands for each OS are on this page.

Is CVE-2025-66565 being exploited?

CVE-2025-66565 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2025-66565 affect?

CVE-2025-66565 affects utils. Severity is critical (CVSS 9.8). 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 UUI

How urgent is CVE-2025-66565?

Priority 49/100. Critical severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2023-2972 CRITICAL 9.8 UPGRADE Prototype Pollution in GitHub repository antfu/utils prior to 0.7.3.
CVE-2021-4277 LOW 2.6 UPGRADE A vulnerability, which was classified as problematic, has been found in fredsmith utils

References

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