CVE-2015-4020: n/a vulnerability

CVE-2015-4020: RubyGems 2.0.x before 2.0.17, 2.2.x before 2.2.5, and 2.4.x before 2.4.8 does not validate the hostname whe...

RubyGems 2.0.x before 2.0.17, 2.2.x before 2.2.5, and 2.4.x before 2.4.8 does not validate the hostname when fetching gems or making API requests, which allows remote attackers to redirect requests to arbitrary domains via a crafted DNS SRV record with a domain that is suffixed with the original domain name, aka a "DNS hijack attack." NOTE: this vulnerability exists because to an incomplete fix for CVE-2015-3900.

UnknownCVSS not scoredNot KEV-listedUpdatedAug 6, 2024, 06:04 UTC (UTC+00:00)

Security readout for executives and security teams

CVE-2015-4020 affects older RubyGems clients. When downloading gems or using the RubyGems API, they could be redirected to an attacker-controlled domain through crafted DNS SRV records because hostname validation was incomplete. Exposure is most likely on legacy Ruby build systems, developer workstations, CI images, or servers still running the affected RubyGems branches. Current systems are unlikely to be exposed unless old Ruby runtimes or pinned RubyGems versions remain in use. Treat as a legacy supply-chain hygiene issue. Prioritize remediation where RubyGems is used in build, deployment, or production dependency workflows, especially if old images are still trusted for releases. Mitigation focus: Upgrade RubyGems beyond the affected branch versions.; Check vendor guidance for packaged Ruby or RubyGems distributions.; Replace legacy CI and build images containing affected RubyGems..

Prepared: Jun 13, 2026, 22:03 UTC (UTC+00:00)

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

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Vulnerability profileCVE Program record

Severity: Unknown
CVSS: Not scored
Known Exploited: No
Published: Aug 25, 2015, 17:00 UTC (UTC+00:00)

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

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5Source links

CVSS and timeline data

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Source materials

CVE List V5 sourceCVE List V5
https://www.trustwave.com/Resources/SpiderLabs-Blog/Attacking-Ruby-Gem-Security-with-CVE-2015-3900/CVE reference · x_refsource_MISC
https://www.trustwave.com/Resources/Security-Advisories/Advisories/TWSL2015-009/?fid=6478CVE reference · x_refsource_MISC
https://github.com/rubygems/rubygems/commit/5c7bfb5CVE reference · x_refsource_CONFIRM
https://puppet.com/security/cve/CVE-2015-3900CVE reference · x_refsource_CONFIRM

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus

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Weakness

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