CVE-2021-3538Network attack vector

Predictable UUIDs via unchecked partial entropy reads

Published Jun 2, 2021 · Updated Aug 3, 2024

Insecure randomness in Satori go.uuid allows attackers to predict UUIDs when consuming applications expose generated identifiers. The rfc4122Generator calls rand.Read into zero-initialized UUID, clock-sequence, and hardware-address buffers but accepts a successful short read, leaving predictable zero bytes. The affected code is limited to pseudoversions from 1.2.1-0.20180103161547-0ef6afb2f6cd before 1.2.1-0.20180404165556-75cca531ea76, and impact depends on consuming software treating UUID unpredictability or uniqueness as a security boundary.

CVSS severity9.8
Critical
EPSS probability2.31%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Insecure randomness in Satori go.uuid allows attackers to predict UUIDs when consuming applications expose generated identifiers. The rfc4122Generator calls rand.Read into zero-initialized UUID, clock-sequence, and hardware-address buffers but accepts a successful short read, leaving predictable zero bytes. The affected code is limited to pseudoversions from 1.2.1-0.20180103161547-0ef6afb2f6cd before 1.2.1-0.20180404165556-75cca531ea76, and impact depends on consuming software treating UUID unpredictability or uniqueness as a security boundary.

The record

CVE
CVE-2021-3538
Published
Jun 2, 2021
Updated
Aug 3, 2024
Vendor
Satori
Product
go.uuid
Classifications
CWE-338
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 2, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=All satori/go.uuid versions from commit 0ef6afb2f6cdd6cdaeee3885a95099c63f18fc8c to d91630c8510268e75203009fe7daf2b8e1d60c45

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Satori · go.uuidversion=All satori/go.uuid versions from commit 0ef6afb2f6cdd6cdaeee3885a95099c63f18fc8c to d91630c8510268e75203009fe7daf2b8e1d60c45

Published CVSS scores

7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
9.3GitHub Advisory DatabaseCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-338Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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