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Fencer Vulns
high 7.5

CVE-2018-8778 json

In Ruby before 2.2.10, 2.3.x before 2.3.7, 2.4.x before 2.4.4, 2.5.x before 2.5.1, and 2.6.0-preview1, an attacker controlling the unpackin…

published 2018-04-03 8 y ago modified 2026-06-17 4 mo ago also EUVD-2018-20387

cvss
7.5
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
7.5%
EPSS 7.5% chance of exploitation in 30 days, percentile 94%
public exploits
0
none known

Summary

In Ruby before 2.2.10, 2.3.x before 2.3.7, 2.4.x before 2.4.4, 2.5.x before 2.5.1, and 2.6.0-preview1, an attacker controlling the unpacking format (similar to format string vulnerabilities) can trigger a buffer under-read in the String#unpack method, resulting in a massive and controlled information disclosure.

Patch / fix

  • ruby-lang ruby 2.2.10, 2.3.7, 2.4.4, 2.5.1
  • ruby2.0 Ubuntu 14.04 LTS 2.0.0.484-1ubuntu2.9
  • ruby2.3 Ubuntu 16.04 LTS 2.3.1-2~16.04.9
  • ruby1.9.1 Ubuntu 14.04 LTS 1.9.3.484-2ubuntu1.11

ubuntu advisories UBUNTU-CVE-2018-8778

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • ruby RHEL 7 2.0.0.648-36.el7
  • ruby-irb RHEL 7 2.0.0.648-36.el7
  • rubygems RHEL 7 2.0.14.1-36.el7
  • ruby-libs RHEL 7 2.0.0.648-36.el7
  • ruby-tcltk RHEL 7 2.0.0.648-36.el7
  • rubygem-json RHEL 7 1.7.7-36.el7
  • rubygem-rake RHEL 7 0.9.6-36.el7
  • rubygem-rdoc RHEL 7 4.0.0-36.el7

red hat advisories RHSA-2020:2288RHSA-2020:2212RHSA-2020:1963RHSA-2019:2028RHSA-2018:3729RHSA-2018:3730

  • ruby2.1 SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +14 more 2.1.9-19.3.2
  • yast2-ruby-bindings SLES for SAP 12 SP2, SLES 12 SP2-LTSS, SLES 12 SP2-BCL +1 more 3.1.53-9.8.1
  • ruby2.5 SLE Module for Basesystem 15 SP1, SLE Module for Basesystem 15 2.5.5-4.3.1

suse advisories SUSE-SU-2020:1570-1SUSE-SU-2019:1804-1

  • ruby2.5 openSUSE Leap 15.1, openSUSE Leap 15.0 2.5.5-lp151.4.3.1
  • ruby-bundled-gems-rpmhelper openSUSE Leap 15.1, openSUSE Leap 15.0 0.0.2-lp151.2.1

opensuse advisories openSUSE-SU-2019:1771-1

  • ruby Alpine 3.24, Alpine 3.23, Alpine 3.22 +14 more 2.5.1-r0
  • ruby Alpine 3.5, Alpine 3.4 2.3.7-r0
  • ruby Alpine 3.7, Alpine 3.6 2.4.4-r0

alpine advisories ALPINE-CVE-2018-8778

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

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-2018-8778 updated cvss 4.8

ruby: Buffer under-read in String#unpack

  • Red Hat Enterprise Linux 5 ruby Red Hat Enterprise Linux 6 ruby, ruby-ri, ruby-irb, ruby-libs, ruby-rdoc, ruby-tcltk Red Hat Software Collections rh-ruby22-ruby, rh-ruby22-ruby-irb, rh-ruby22-rubygems, rh-ruby22-ruby-libs, rh-ruby22-ruby-tcltk, rh-ruby22-rubygem-json, +8 more Red Hat Subscription Asset Manager ruby193-ruby
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Enterprise Linux Client (v. 7) ruby 2.0.0.648-36.el7, rubygems 2.0.14.1-36.el7, ruby-irb 2.0.0.648-36.el7, rubygem-json 1.7.7-36.el7, rubygem-rdoc 4.0.0-36.el7, ruby-libs 2.0.0.648-36.el7, +3 more Red Hat Enterprise Linux Client Optional (v. 7) rubygem-rake 0.9.6-36.el7, ruby-tcltk 2.0.0.648-36.el7, rubygem-minitest 4.3.2-36.el7 Red Hat Enterprise Linux ComputeNode (v. 7) ruby 2.0.0.648-36.el7, rubygems 2.0.14.1-36.el7, ruby-irb 2.0.0.648-36.el7, rubygem-json 1.7.7-36.el7, rubygem-rdoc 4.0.0-36.el7, ruby-libs 2.0.0.648-36.el7, +3 more
    fixed: vendor fix RHSA-2019:2028
  • Red Hat Enterprise Linux ComputeNode EUS (v. 7.5) ruby 2.0.0.648-36.el7_5, rubygems 2.0.14.1-36.el7_5, ruby-irb 2.0.0.648-36.el7_5, rubygem-json 1.7.7-36.el7_5, rubygem-rdoc 4.0.0-36.el7_5, ruby-libs 2.0.0.648-36.el7_5, +3 more
    fixed: vendor fix RHSA-2020:1963
  • Red Hat Enterprise Linux ComputeNode EUS (v. 7.6) ruby 2.0.0.648-37.el7_6, rubygems 2.0.14.1-37.el7_6, ruby-irb 2.0.0.648-37.el7_6, rubygem-json 1.7.7-37.el7_6, rubygem-rdoc 4.0.0-37.el7_6, ruby-libs 2.0.0.648-37.el7_6, +3 more
    fixed: vendor fix RHSA-2020:2288
  • Red Hat Enterprise Linux ComputeNode Optional (v. 7) rubygem-rake 0.9.6-36.el7, ruby-tcltk 2.0.0.648-36.el7, rubygem-minitest 4.3.2-36.el7
    fixed: vendor fix RHSA-2019:2028
  • Red Hat Enterprise Linux ComputeNode Optional EUS (v. 7.5) rubygem-rake 0.9.6-36.el7_5, ruby-tcltk 2.0.0.648-36.el7_5, rubygem-minitest 4.3.2-36.el7_5
    fixed: vendor fix RHSA-2020:1963
  • Red Hat Enterprise Linux ComputeNode Optional EUS (v. 7.6) rubygem-rake 0.9.6-37.el7_6, ruby-tcltk 2.0.0.648-37.el7_6, rubygem-minitest 4.3.2-37.el7_6 Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server (v. 7) ruby 2.0.0.648-37.el7_6, rubygems 2.0.14.1-37.el7_6, ruby-irb 2.0.0.648-37.el7_6, rubygem-json 1.7.7-37.el7_6, rubygem-rdoc 4.0.0-37.el7_6, ruby-libs 2.0.0.648-37.el7_6, +3 more Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server Optional (v. 7) rubygem-rake 0.9.6-37.el7_6, ruby-tcltk 2.0.0.648-37.el7_6, rubygem-minitest 4.3.2-37.el7_6
    fixed: vendor fix RHSA-2020:2288
  • Red Hat Enterprise Linux Server (v. 7) ruby 2.0.0.648-36.el7, rubygems 2.0.14.1-36.el7, ruby-irb 2.0.0.648-36.el7, rubygem-json 1.7.7-36.el7, rubygem-rdoc 4.0.0-36.el7, ruby-libs 2.0.0.648-36.el7, +3 more
    fixed: vendor fix RHSA-2019:2028
show 11 more
  • Red Hat Enterprise Linux Server AUS (v. 7.4) ruby 2.0.0.648-36.el7_4, rubygems 2.0.14.1-36.el7_4, ruby-irb 2.0.0.648-36.el7_4, rubygem-json 1.7.7-36.el7_4, rubygem-rdoc 4.0.0-36.el7_4, ruby-libs 2.0.0.648-36.el7_4, +3 more Red Hat Enterprise Linux Server E4S (v. 7.4) ruby 2.0.0.648-36.el7_4, rubygems 2.0.14.1-36.el7_4, ruby-irb 2.0.0.648-36.el7_4, rubygem-json 1.7.7-36.el7_4, rubygem-rdoc 4.0.0-36.el7_4, ruby-libs 2.0.0.648-36.el7_4, +3 more
    fixed: vendor fix RHSA-2020:2212
  • Red Hat Enterprise Linux Server EUS (v. 7.5) ruby 2.0.0.648-36.el7_5, rubygems 2.0.14.1-36.el7_5, ruby-irb 2.0.0.648-36.el7_5, rubygem-json 1.7.7-36.el7_5, rubygem-rdoc 4.0.0-36.el7_5, ruby-libs 2.0.0.648-36.el7_5, +3 more
    fixed: vendor fix RHSA-2020:1963
  • Red Hat Enterprise Linux Server EUS (v. 7.6) ruby 2.0.0.648-37.el7_6, rubygems 2.0.14.1-37.el7_6, ruby-irb 2.0.0.648-37.el7_6, rubygem-json 1.7.7-37.el7_6, rubygem-rdoc 4.0.0-37.el7_6, ruby-libs 2.0.0.648-37.el7_6, +3 more
    fixed: vendor fix RHSA-2020:2288
  • Red Hat Enterprise Linux Server Optional (v. 7) rubygem-rake 0.9.6-36.el7, ruby-tcltk 2.0.0.648-36.el7, rubygem-minitest 4.3.2-36.el7
    fixed: vendor fix RHSA-2019:2028
  • Red Hat Enterprise Linux Server Optional AUS (v. 7.4) rubygem-rake 0.9.6-36.el7_4, ruby-tcltk 2.0.0.648-36.el7_4, rubygem-minitest 4.3.2-36.el7_4 Red Hat Enterprise Linux Server Optional E4S (v. 7.4) rubygem-rake 0.9.6-36.el7_4, ruby-tcltk 2.0.0.648-36.el7_4, rubygem-minitest 4.3.2-36.el7_4
    fixed: vendor fix RHSA-2020:2212
  • Red Hat Enterprise Linux Server Optional EUS (v. 7.5) rubygem-rake 0.9.6-36.el7_5, ruby-tcltk 2.0.0.648-36.el7_5, rubygem-minitest 4.3.2-36.el7_5
    fixed: vendor fix RHSA-2020:1963
  • Red Hat Enterprise Linux Server Optional EUS (v. 7.6) rubygem-rake 0.9.6-37.el7_6, ruby-tcltk 2.0.0.648-37.el7_6, rubygem-minitest 4.3.2-37.el7_6
    fixed: vendor fix RHSA-2020:2288
  • Red Hat Enterprise Linux Server Optional TUS (v. 7.4) rubygem-rake 0.9.6-36.el7_4, ruby-tcltk 2.0.0.648-36.el7_4, rubygem-minitest 4.3.2-36.el7_4 Red Hat Enterprise Linux Server TUS (v. 7.4) ruby 2.0.0.648-36.el7_4, rubygems 2.0.14.1-36.el7_4, ruby-irb 2.0.0.648-36.el7_4, rubygem-json 1.7.7-36.el7_4, rubygem-rdoc 4.0.0-36.el7_4, ruby-libs 2.0.0.648-36.el7_4, +3 more
    fixed: vendor fix RHSA-2020:2212
  • Red Hat Enterprise Linux Workstation (v. 7) ruby 2.0.0.648-36.el7, rubygems 2.0.14.1-36.el7, ruby-irb 2.0.0.648-36.el7, rubygem-json 1.7.7-36.el7, rubygem-rdoc 4.0.0-36.el7, ruby-libs 2.0.0.648-36.el7, +3 more Red Hat Enterprise Linux Workstation Optional (v. 7) rubygem-rake 0.9.6-36.el7, ruby-tcltk 2.0.0.648-36.el7, rubygem-minitest 4.3.2-36.el7
    fixed: vendor fix RHSA-2019:2028
  • Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 6) rh-ruby23-ruby 2.3.8-69.el6, rh-ruby24-ruby 2.4.5-91.el6, rh-ruby23-ruby-irb 2.3.8-69.el6, rh-ruby24-ruby-irb 2.4.5-91.el6, rh-ruby23-ruby-libs 2.3.8-69.el6, rh-ruby24-ruby-libs 2.4.5-91.el6, +27 more Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 7) rh-ruby25-ruby 2.5.3-6.el7, rh-ruby23-ruby 2.3.8-69.el7, rh-ruby24-ruby 2.4.5-91.el7, rh-ruby25-ruby-irb 2.5.3-6.el7, rh-ruby25-rubygems 2.7.6-6.el7, rh-ruby23-ruby-irb 2.3.8-69.el7, +44 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.4) rh-ruby25-ruby 2.5.3-6.el7, rh-ruby23-ruby 2.3.8-69.el7, rh-ruby24-ruby 2.4.5-91.el7, rh-ruby25-ruby-irb 2.5.3-6.el7, rh-ruby25-rubygems 2.7.6-6.el7, rh-ruby23-ruby-irb 2.3.8-69.el7, +44 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.5) rh-ruby25-ruby 2.5.3-6.el7, rh-ruby23-ruby 2.3.8-69.el7, rh-ruby24-ruby 2.4.5-91.el7, rh-ruby25-ruby-irb 2.5.3-6.el7, rh-ruby25-rubygems 2.7.6-6.el7, rh-ruby23-ruby-irb 2.3.8-69.el7, +44 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.6) rh-ruby25-ruby 2.5.3-6.el7, rh-ruby23-ruby 2.3.8-69.el7, rh-ruby24-ruby 2.4.5-91.el7, rh-ruby25-ruby-irb 2.5.3-6.el7, rh-ruby25-rubygems 2.7.6-6.el7, rh-ruby23-ruby-irb 2.3.8-69.el7, +44 more Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 6) rh-ruby23-ruby 2.3.8-69.el6, rh-ruby24-ruby 2.4.5-91.el6, rh-ruby23-ruby-irb 2.3.8-69.el6, rh-ruby24-ruby-irb 2.4.5-91.el6, rh-ruby23-ruby-libs 2.3.8-69.el6, rh-ruby24-ruby-libs 2.4.5-91.el6, +27 more
    +1 more products
    Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 7) rh-ruby25-ruby 2.5.3-6.el7, rh-ruby23-ruby 2.3.8-69.el7, rh-ruby24-ruby 2.4.5-91.el7, rh-ruby25-ruby-irb 2.5.3-6.el7, rh-ruby25-rubygems 2.7.6-6.el7, rh-ruby23-ruby-irb 2.3.8-69.el7, +44 more
    fixed: vendor fix RHSA-2018:3729
  • Red Hat Enterprise Linux 8 ruby, ruby-irb, rubygems, ruby-libs, rubygem-pg, rubygem-irb, +25 more
    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

7.53% chance of exploitation in the next 30 days, higher than 94% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.0 7.5 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:P/I:N/A:N

Classification

Weakness
  • CWE-134 Use of Externally-Controlled Format String

References

Sources

Fencer Vulns 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.