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Fencer Vulns
medium 5.3

CVE-2020-10933 json

An issue was discovered in Ruby 2.5.x through 2.5.7, 2.6.x through 2.6.5, and 2.7.0.

published 2020-05-04 6 y ago modified 2026-09-08 2 mo ago also BIT-ruby-2020-10933 , BIT-ruby-min-2020-10933 , EUVD-2020-3339

cvss
5.3
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.5%
EPSS 2.5% chance of exploitation in 30 days, percentile 84%
public exploits
0
none known

Summary

An issue was discovered in Ruby 2.5.x through 2.5.7, 2.6.x through 2.6.5, and 2.7.0. If a victim calls BasicSocket#read_nonblock(requested_size, buffer, exception: false), the method resizes the buffer to fit the requested size, but no data is copied. Thus, the buffer string provides the previous value of the heap. This may expose possibly sensitive data from the interpreter.

Patch / fix

  • bitnami ruby 2.5.8, 2.6.6, 2.7.1
  • bitnami ruby-min 2.5.8, 2.6.6, 2.7.1
  • ruby2.7 Debian 11 2.7.1-1

debian advisories DEBIAN-CVE-2020-10933

  • ruby2.5 Ubuntu 18.04 LTS 2.5.1-1ubuntu1.8
  • ruby2.7 Ubuntu 20.04 LTS 2.7.0-5ubuntu1.3

ubuntu advisories UBUNTU-CVE-2020-10933

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

  • rubygem-pg RHEL 8, RHEL 8.2 EUS, RHEL 8.1 E4S 1.1.4-1.module+el8.1.0+3653+beb38eb0
  • rubygem-abrt RHEL 8, RHEL 8.2 EUS, RHEL 8.1 E4S 0.3.0-4.module+el8.1.0+3653+beb38eb0
  • rubygem-bson RHEL 8, RHEL 8.2 EUS, RHEL 8.1 E4S 4.5.0-1.module+el8.1.0+3653+beb38eb0
  • rubygem-mongo RHEL 8, RHEL 8.2 EUS, RHEL 8.1 E4S 2.8.0-1.module+el8.1.0+3653+beb38eb0
  • ruby RHEL 8 2.6.7-107.module+el8.4.0+10830+bbd85cce
  • rubygems RHEL 8 3.0.3.1-107.module+el8.4.0+10830+bbd85cce
  • ruby-libs RHEL 8 2.6.7-107.module+el8.4.0+10830+bbd85cce
  • rubygem-irb RHEL 8 1.0.0-107.module+el8.4.0+10830+bbd85cce

red hat advisories RHSA-2022:0582RHSA-2022:0581RHSA-2021:2588RHSA-2021:2587RHSA-2021:2230RHSA-2021:2104

  • ruby2.5 SLE Module for Basesystem 15 SP1 2.5.8-4.11.1

suse advisories SUSE-SU-2020:0995-1

  • ruby4.0 openSUSE Tumbleweed 4.0.0~preview2-1.1
  • ruby3.4 openSUSE Tumbleweed 3.4.1-1.1
  • ruby2.7 openSUSE Tumbleweed 2.7.3-3.2
  • ruby3.0 openSUSE Tumbleweed 3.0.1-3.2
  • ruby3.1 openSUSE Tumbleweed 3.1.0-1.1
  • ruby3.2 openSUSE Tumbleweed 3.2.1-1.1
  • ruby3.3 openSUSE Tumbleweed 3.3.0-1.2
  • ruby2.5 openSUSE Leap 15.1 2.5.8-lp151.4.9.1

opensuse advisories openSUSE-SU-2025:15819-1openSUSE-SU-2025:14621-1openSUSE-SU-2024:11310-1openSUSE-SU-2024:11311-1openSUSE-SU-2024:11786-1openSUSE-SU-2024:12712-1

  • rubygem-pg AlmaLinux 8 1.1.4-1.module_el8.5.0+250+ba22dbf7
  • rubygem-pg AlmaLinux 8 1.1.4-1.module_el8.5.0+2623+08a8ba32
  • rubygem-abrt AlmaLinux 8 0.3.0-4.module_el8.5.0+259+8cec6917
  • rubygem-abrt AlmaLinux 8 0.3.0-4.module_el8.5.0+2623+08a8ba32
  • rubygem-bson AlmaLinux 8 4.5.0-1.module_el8.5.0+2623+08a8ba32
  • rubygem-bson AlmaLinux 8 4.5.0-1.module_el8.5.0+250+ba22dbf7
  • rubygem-mongo AlmaLinux 8 2.8.0-1.module_el8.5.0+250+ba22dbf7
  • rubygem-mongo AlmaLinux 8 2.8.0-1.module_el8.5.0+2623+08a8ba32

almalinux advisories ALSA-2021:2588ALSA-2021:2587

  • ruby Rocky Linux 8 2.6.7-107.module+el8.4.0+593+8d7f9f0c
  • rubygem-pg Rocky Linux 8 1.1.4-1.module+el8.5.0+738+032c9c02
  • rubygem-pg Rocky Linux 8 1.1.4-1.module+el8.4.0+446+80b53620
  • rubygem-pg Rocky Linux 8 1.1.4-1.module+el8.4.0+593+8d7f9f0c
  • rubygem-abrt Rocky Linux 8 0.3.0-4.module+el8.5.0+738+032c9c02
  • rubygem-abrt Rocky Linux 8 0.3.0-4.module+el8.3.0+167+5c390590
  • rubygem-abrt Rocky Linux 8 0.3.0-4.module+el8.4.0+592+03ff458a
  • rubygem-bson Rocky Linux 8 4.5.0-1.module+el8.4.0+593+8d7f9f0c

rocky linux advisories RLSA-2021:2588RLSA-2021:2587

  • ruby Alpine 3.10, Alpine 3.9, Alpine 3.8 2.5.8-r0
  • ruby Alpine 3.24, Alpine 3.23, Alpine 3.22 +11 more 2.6.6-r0

alpine advisories ALPINE-CVE-2020-10933

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-2020-10933 updated cvss 5.3

ruby: BasicSocket#read_nonblock method leads to information disclosure

  • Red Hat Enterprise Linux AppStream (v. 8) ruby 2.5.9-107.module+el8.4.0+10822+fe4fffb1, ruby 2.6.7-107.module+el8.4.0+10830+bbd85cce, rubygem-pg 1.0.0-2.module+el8.1.0+3656+f80bfa1d, rubygem-pg 1.1.4-1.module+el8.1.0+3653+beb38eb0, ruby-irb 2.5.9-107.module+el8.4.0+10822+fe4fffb1, ruby-libs 2.5.9-107.module+el8.4.0+10822+fe4fffb1, +40 more
    fixed: vendor fix RHSA-2021:2587
  • Red Hat Enterprise Linux AppStream E4S (v. 8.1) ruby 2.6.9-107.module+el8.1.0+14088+04cf326e, rubygem-pg 1.1.4-1.module+el8.1.0+3653+beb38eb0, ruby-libs 2.6.9-107.module+el8.1.0+14088+04cf326e, rubygem-abrt 0.3.0-4.module+el8.1.0+3653+beb38eb0, rubygem-bson 4.5.0-1.module+el8.1.0+3653+beb38eb0, rubygem-mongo 2.8.0-1.module+el8.1.0+3653+beb38eb0, +17 more
    fixed: vendor fix RHSA-2022:0581
  • Red Hat Enterprise Linux AppStream EUS (v. 8.2) ruby 2.6.9-107.module+el8.2.0+14086+86d863af, rubygem-pg 1.1.4-1.module+el8.1.0+3653+beb38eb0, ruby-libs 2.6.9-107.module+el8.2.0+14086+86d863af, rubygem-abrt 0.3.0-4.module+el8.1.0+3653+beb38eb0, rubygem-bson 4.5.0-1.module+el8.1.0+3653+beb38eb0, rubygem-mongo 2.8.0-1.module+el8.1.0+3653+beb38eb0, +17 more
    fixed: vendor fix RHSA-2022:0582
  • Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 7) rh-ruby25-ruby 2.5.9-9.el7, rh-ruby26-ruby 2.6.7-119.el7, rh-ruby25-ruby-irb 2.5.9-9.el7, rh-ruby25-ruby-libs 2.5.9-9.el7, rh-ruby25-rubygems 2.7.6.3-9.el7, rh-ruby26-ruby-libs 2.6.7-119.el7, +29 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.6) rh-ruby25-ruby 2.5.9-9.el7, rh-ruby25-ruby-irb 2.5.9-9.el7, rh-ruby25-ruby-libs 2.5.9-9.el7, rh-ruby25-rubygems 2.7.6.3-9.el7, rh-ruby25-rubygem-json 2.1.0-9.el7, rh-ruby25-rubygem-psych 3.0.2-9.el7, +11 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.7) rh-ruby25-ruby 2.5.9-9.el7, rh-ruby26-ruby 2.6.7-119.el7, rh-ruby25-ruby-irb 2.5.9-9.el7, rh-ruby25-ruby-libs 2.5.9-9.el7, rh-ruby25-rubygems 2.7.6.3-9.el7, rh-ruby26-ruby-libs 2.6.7-119.el7, +29 more Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 7) rh-ruby25-ruby 2.5.9-9.el7, rh-ruby26-ruby 2.6.7-119.el7, rh-ruby25-ruby-irb 2.5.9-9.el7, rh-ruby25-ruby-libs 2.5.9-9.el7, rh-ruby25-rubygems 2.7.6.3-9.el7, rh-ruby26-ruby-libs 2.6.7-119.el7, +29 more
    fixed: vendor fix RHSA-2021:2104
  • Red Hat CloudForms Management Engine 5 ruby, ruby-irb, rubygems, ruby-libs, rubygem-rake, rubygem-rdoc, +10 more Red Hat Enterprise Linux 5 ruby Red Hat Enterprise Linux 6 ruby, ruby-ri, ruby-irb, ruby-libs, ruby-rdoc, ruby-tcltk Red Hat Enterprise Linux 7 ruby, ruby-irb, rubygems, ruby-libs, ruby-tcltk, rubygem-json, +6 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

2.53% chance of exploitation in the next 30 days, higher than 84% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • ruby-lang.org https://www.ruby-lang.org/en/news/2020/03/31/heap-exposure-in-socket-cve-2020-10933/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:P/I:N/A:N
OSV 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Affected packages

ecosystem package affected fixed in
bitnami ruby
>=2.5.0, <2.5.8
>=2.6.0, <2.6.6
>=2.7.0, <2.7.1
2.5.8
2.6.6
2.7.1
bitnami ruby-min
>=2.5.0, <2.5.8
>=2.6.0, <2.6.6
>=2.7.0, <2.7.1
2.5.8
2.6.6
2.7.1

Classification

Weakness
  • CWE-908 Use of Uninitialized Resource

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.