CVE-2021-29499Network attack vector

Predictable UUIDs via insecure dependency randomness

Published May 7, 2021 · Updated Aug 3, 2024

Insufficient randomness in Sylabs SIF 1.2.2 and earlier allows attackers to predict UUIDs via newly created container images. The siftool new command and siftool.New function delegate UUID generation to satori/go.uuid v1.2.0, whose NewV4 output can contain large predictable zero-filled regions. Exploitation requires access to a generated SIF identifier; published evidence establishes weakened identifier unpredictability, not code execution or direct data access.

CVSS severity7.5
High
EPSS probability0.96%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Insufficient randomness in Sylabs SIF 1.2.2 and earlier allows attackers to predict UUIDs via newly created container images. The siftool new command and siftool.New function delegate UUID generation to satori/go.uuid v1.2.0, whose NewV4 output can contain large predictable zero-filled regions. Exploitation requires access to a generated SIF identifier; published evidence establishes weakened identifier unpredictability, not code execution or direct data access.

The record

CVE
CVE-2021-29499
Published
May 7, 2021
Updated
Aug 3, 2024
Vendor
Sylabs
Product
Singularity Image Format (SIF)
Classifications
CWE-330
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 7, 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=<= 1.2.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Sylabs · Singularity Image Format (SIF)version=<= 1.2.2

Published CVSS scores

7.5GitHub CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
7.5UbuntuCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

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-330Use of Insufficiently Random Values

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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