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Fencer Intel
medium 4.3

CVE-2015-4020 json

RubyGems Improper Input Validation vulnerability

published 2015-08-25 11 y ago modified 2026-06-17 4 mo ago also GHSA-qv62-xfj6-32xm , EUVD-2022-5031

cvss
4.3
version 2.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
3.5%
EPSS 3.5% chance of exploitation in 30 days, percentile 89%
public exploits
0
none known

Summary

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.

Patch / fix

  • rubygems rubygems-update 2.0.17, 2.2.5, 2.4.8

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2015-4020 updated cvss 7.9

rubygems: incomplete fix for CVE-2015-3900

  • Red Hat CloudForms Management Engine 5 rubygems Red Hat OpenStack Foreman rubygems Red Hat Enterprise Linux 5 ruby Red Hat Enterprise Linux 6 ruby, ruby-ri, ruby-irb, rubygems, ruby-libs, ruby-rdoc, +1 more Red Hat Enterprise Linux 7 ruby, ruby-irb, rubygems, ruby-libs, ruby-tcltk, rubygem-json, +6 more Red Hat Enterprise Linux OpenStack Platform 5 (Icehouse) rubygems
    +5 more products
    Red Hat Enterprise MRG 2 rubygems Red Hat OpenShift Enterprise 2 rubygems Red Hat Satellite 6 rubygems Red Hat Software Collections ruby193-ruby, ruby200-ruby, rh-ruby22-ruby, ruby193-ruby-irb, ruby193-rubygems, ruby200-ruby-irb, +31 more Red Hat Subscription Asset Manager ruby193-ruby
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

3.46% chance of exploitation in the next 30 days, higher than 89% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N

Affected packages

ecosystem package affected fixed in
rubygems rubygems-update
<2.0.17
>=2.1.0.rc.1, <2.2.5
>=2.3.0, <2.4.8
2.0.17
2.2.5
2.4.8

Classification

Weakness
  • CWE-20 Improper Input Validation

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.