HOME VULNERABILITIESCVE-2015-4020

MEDIUM

CVE-2015-4020

CWE-20Published: August 25, 2015· Updated: Jun 17, 2026

4.3

CVSS v3.1

Official Description

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.

Technical Analysis

CVE-2015-4020 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation requires some privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

CVSS v3.1 Vector Breakdown

Exploitability

Attack VectorNetwork

Attack ComplexityM

Privileges Req.

User Interaction

Scope

Impact

ConfidentialityNone

IntegrityP

AvailabilityNone

AV:N/AC:M/Au:N/C:N/I:P/A:N

Affected Vendors & Products

Oracle1 product(s)

solaris

rubygems1 product(s)

rubygems

Source: NVD CPE · 31 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time

Offensive Security exploit database

GitHub PoC Search

Community PoC repositories

Rapid7 / Metasploit

Metasploit module search

Security advisories & exploits

Official NIST entry

CVE Program entry

External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

ADVISORYhttp://blog.rubygems.org/2015/06/08/2.2.5-released.html

ADVISORYhttp://blog.rubygems.org/2015/06/08/2.4.8-released.html

ADVISORYhttp://www.oracle.com/technetwork/topics/security/bulletinoct2015-2511968.html

ADVISORYhttps://www.trustwave.com/Resources/Security-Advisories/Advisories/TWSL2015-009/?fid=6478

ADVISORYhttps://www.trustwave.com/Resources/SpiderLabs-Blog/Attacking-Ruby-Gem-Security-with-CVE-2015-3900/

ADVISORYhttp://blog.rubygems.org/2015/06/08/2.2.5-released.html

ADVISORYhttp://blog.rubygems.org/2015/06/08/2.4.8-released.html

ADVISORYhttp://www.oracle.com/technetwork/topics/security/bulletinoct2015-2511968.html

ADVISORYhttps://www.trustwave.com/Resources/Security-Advisories/Advisories/TWSL2015-009/?fid=6478

ADVISORYhttps://www.trustwave.com/Resources/SpiderLabs-Blog/Attacking-Ruby-Gem-Security-with-CVE-2015-3900/

All References (16)

→

http://blog.rubygems.org/2015/06/08/2.2.5-released.htmlVendor Advisory

→

http://blog.rubygems.org/2015/06/08/2.4.8-released.htmlVendor Advisory

→

http://www.oracle.com/technetwork/topics/security/bulletinoct2015-2511968.htmlThird Party Advisory

→

http://www.securityfocus.com/bid/75431

→

https://github.com/rubygems/rubygems/commit/5c7bfb5

→

https://puppet.com/security/cve/CVE-2015-3900

→

https://www.trustwave.com/Resources/Security-Advisories/Advisories/TWSL2015-009/?fid=6478Third Party Advisory

→

https://www.trustwave.com/Resources/SpiderLabs-Blog/Attacking-Ruby-Gem-Security-with-CVE-2015-3900/Third Party Advisory

→

http://blog.rubygems.org/2015/06/08/2.2.5-released.htmlVendor Advisory

→

http://blog.rubygems.org/2015/06/08/2.4.8-released.htmlVendor Advisory

→

http://www.oracle.com/technetwork/topics/security/bulletinoct2015-2511968.htmlThird Party Advisory

→

http://www.securityfocus.com/bid/75431

→

https://github.com/rubygems/rubygems/commit/5c7bfb5

→

https://puppet.com/security/cve/CVE-2015-3900

→

https://www.trustwave.com/Resources/Security-Advisories/Advisories/TWSL2015-009/?fid=6478Third Party Advisory

Quick Facts

CVE IDCVE-2015-4020

CVSS Score4.3 / 10

SeverityMEDIUM

WeaknessCWE-20

CISA KEVNo

Affected2 vendor(s)

PublishedAug 25, 2015

Related CVEs (CWE-20)

Recommended Actions

→Apply vendor patches immediately
→Monitor CVE-2015-4020 in threat intel feeds
→Review IDS/IPS signatures for exploitation attempts

Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.

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