CVE-2021-28966Public exploitNetwork attack vector

Arbitrary file and directory creation via path traversal

Published Jul 27, 2021 · Updated Aug 3, 2024

Path traversal in Ruby 2.7.2 and earlier and 3.0.0 on Windows allows remote attackers to create files or directories via crafted paths. Dir.mktmpdir accepts a prefix containing '..' and uses it to select a creation target outside the intended temporary directory. Exposure requires an application to pass attacker-controlled input as the prefix and filesystem permissions that permit creation at the resolved target.

CVSS severity7.5
High
EPSS probability57.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Path traversal in Ruby 2.7.2 and earlier and 3.0.0 on Windows allows remote attackers to create files or directories via crafted paths. Dir.mktmpdir accepts a prefix containing '..' and uses it to select a creation target outside the intended temporary directory. Exposure requires an application to pass attacker-controlled input as the prefix and filesystem permissions that permit creation at the resolved target.

The record

CVE
CVE-2021-28966
Published
Jul 27, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-22, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 27, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:P/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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
T1190Exploit Public-Facing Application

Public exploit references

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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