CVE-2023-40165Public exploitNetwork attack vector

Gem replacement via mismatched specification names

Published Aug 17, 2023 · Updated Oct 1, 2024

Improper input validation in RubyGems.org before 2023-08-14 allows remote attackers to replace certain published gems. The upload path used Gem::Specification#original_name as the storage filename without ensuring that it matched the new version's full_name, so a crafted YAML gemspec addressed an existing object. The target must have a platform, version, or gem name matching /-\d/; replacement purges the CDN and serves the malicious gem to later downloaders.

CVSS severity7.4
High
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in RubyGems.org before 2023-08-14 allows remote attackers to replace certain published gems. The upload path used Gem::Specification#original_name as the storage filename without ensuring that it matched the new version's full_name, so a crafted YAML gemspec addressed an existing object. The target must have a platform, version, or gem name matching /-\d/; replacement purges the CDN and serves the malicious gem to later downloaders.

The record

CVE
CVE-2023-40165
Published
Aug 17, 2023
Updated
Oct 1, 2024
Vendor
RubyGems
Product
RubyGems.org
Classifications
CWE-20, T1195.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 17, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 1, 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=< 2023-08-14

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

RubyGems · RubyGems.orgversion=< 2023-08-14

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
7.4GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:H/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 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 exploitPublished

Weakness, pattern, technique

CWE-20Improper Input Validation
T1195.002Compromise Software Supply Chain

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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