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Fencer Vulns
high 7.5

CVE-2021-41817 json

Regular expression denial of service vulnerability (ReDoS) in date

published 2021-11-16 4 y ago modified 2026-09-08 2 mo ago also BIT-ruby-2021-41817 , BIT-ruby-min-2021-41817 , EUVD-2021-2381 , GHSA-qg54-694p-wgpp , JLSEC-2026-1287

cvss
7.5
version 3.1, 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

Date.parse in the date gem through 3.2.0 for Ruby allows ReDoS (regular expression Denial of Service) via a long string. The fixed versions are 3.2.1, 3.1.2, 3.0.2, and 2.0.1.

Patch / fix

  • rubygems date 2.0.1, 3.0.2, 3.1.2, 3.2.1
  • bitnami ruby 2.6.9, 2.7.5, 3.0.3
  • bitnami ruby-min 2.6.9, 2.7.5, 3.0.3
  • ruby-lang date 2.0.1, 3.0.2, 3.1.2
  • ruby-lang ruby 2.6.9, 2.7.5, 3.0.3
  • ruby2.7 Debian 11 2.7.4-1+deb11u1

debian advisories DEBIAN-CVE-2021-41817

  • ruby2.5 Ubuntu 18.04 LTS 2.5.1-1ubuntu1.11
  • ruby2.7 Ubuntu 20.04 LTS 2.7.0-5ubuntu1.6
  • ruby3.0 Ubuntu 22.04 LTS 3.0.2-7ubuntu2
  • ruby2.3 Ubuntu Pro 16.04 LTS 2.3.1-2~ubuntu16.04.16+esm2

ubuntu advisories UBUNTU-CVE-2021-41817

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 8.4 EUS, RHEL 8.2 EUS +1 more 1.1.4-1.module+el8.1.0+3653+beb38eb0
  • rubygem-abrt RHEL 8, RHEL 8.4 EUS, RHEL 8.2 EUS +1 more 0.3.0-4.module+el8.1.0+3653+beb38eb0
  • rubygem-bson RHEL 8, RHEL 8.4 EUS, RHEL 8.2 EUS +1 more 4.5.0-1.module+el8.1.0+3653+beb38eb0
  • rubygem-mongo RHEL 8, RHEL 8.4 EUS, RHEL 8.2 EUS +1 more 2.8.0-1.module+el8.1.0+3653+beb38eb0
  • ruby RHEL 8 3.0.4-141.module+el8.6.0+16311+3e5e17e9
  • rubygems RHEL 8 3.2.33-141.module+el8.6.0+16311+3e5e17e9
  • ruby-libs RHEL 8 3.0.4-141.module+el8.6.0+16311+3e5e17e9
  • rubygem-pg RHEL 8 1.2.3-1.module+el8.5.0+11580+845038eb

red hat advisories RHSA-2022:0582RHSA-2022:0581RHSA-2022:6450RHSA-2022:6447RHSA-2022:6856RHSA-2022:6855

  • ruby2.5 SLES for SAP 15 SP3, SLES for SAP 15 SP2, SLES for SAP 15 SP1 +14 more 2.5.9-150000.4.29.1
  • ruby2.5 SLES for SAP 15 SP2, SLES for SAP 15 SP1, SLES for SAP 15 +21 more 2.5.9-150000.4.23.1

suse advisories SUSE-SU-2023:4176-1SUSE-SU-2022:1512-1

  • ruby4.0 openSUSE Tumbleweed 4.0.0~preview2-1.1
  • ruby3.4 openSUSE Tumbleweed 3.4.1-1.1
  • ruby2.7 openSUSE Tumbleweed 2.7.5-1.1
  • ruby3.0 openSUSE Tumbleweed 3.0.3-1.1
  • 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

opensuse advisories openSUSE-SU-2025:15819-1openSUSE-SU-2025:14621-1openSUSE-SU-2024:11657-1openSUSE-SU-2024:11658-1openSUSE-SU-2024:11786-1openSUSE-SU-2024:12712-1

  • ruby AlmaLinux 8 2.7.6-138.module_el8.6.0+3263+904da987
  • rubygems AlmaLinux 8 3.1.6-138.module_el8.6.0+3263+904da987
  • ruby-libs AlmaLinux 8 2.7.6-138.module_el8.6.0+3263+904da987
  • rubygem-pg AlmaLinux 8 1.2.3-1.module_el8.5.0+2595+0c654ebc
  • rubygem-pg AlmaLinux 8 1.2.3-1.module_el8.5.0+117+35d1289b
  • rubygem-pg AlmaLinux 8 1.2.3-1.module_el8.4.0+2399+4e3a532a
  • rubygem-pg AlmaLinux 8 1.2.3-1.module_el8.6.0+3167+957ef55e
  • rubygem-irb AlmaLinux 8 1.2.6-138.module_el8.6.0+3263+904da987

almalinux advisories ALSA-2022:6447ALSA-2022:6450ALSA-2022:5779ALSA-2022:0543

  • ruby Rocky Linux 8 3.0.4-141.module+el8.6.0+1002+a7dba0ac
  • rubygem-pg Rocky Linux 8 1.2.3-1.module+el8.5.0+668+665814fa
  • rubygem-pg Rocky Linux 8 1.2.3-1.module+el8.4.0+411+b946f28c
  • rubygem-pg Rocky Linux 8 1.2.3-1.module+el8.4.0+594+11b6673a
  • rubygem-abrt Rocky Linux 8 0.4.0-1.module+el8.5.0+668+665814fa
  • rubygem-abrt Rocky Linux 8 0.4.0-1.module+el8.4.0+411+b946f28c
  • rubygem-abrt Rocky Linux 8 0.4.0-1.module+el8.4.0+594+11b6673a
  • rubygem-mysql2 Rocky Linux 8 0.5.3-1.module+el8.5.0+668+665814fa

rocky linux advisories RLSA-2022:6450RLSA-2022:6447RLSA-2022:5779RLSA-2022:0543

  • ruby Alpine 3.14, Alpine 3.13, Alpine 3.12 2.7.5-r0
  • ruby Alpine 3.24, Alpine 3.23, Alpine 3.22 +7 more 3.0.3-r0

alpine advisories ALPINE-CVE-2021-41817

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

  • ruby CBL-Mariner 2.0 3.1.2-2

azure linux advisories AZL-7110

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

  • ruby Arch Linux 3.0.3-1

arch linux advisories AVG-2555

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-2021-41817 updated cvss 7.5

ruby: Regular expression denial of service vulnerability of Date parsing methods

  • Red Hat Enterprise Linux 6 ruby, ruby-ri, ruby-irb, ruby-libs, ruby-rdoc, ruby-tcltk
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 7 ruby, ruby-irb, rubygems, ruby-libs, ruby-tcltk, rubygem-json, +6 more
    affected: no fix planned “Will not fix”
  • Red Hat Enterprise Linux AppStream (v. 8) ruby 2.5.9-110.module+el8.6.0+15956+aa803fc1, ruby 2.6.9-108.module+el8.5.0+13719+08a8ba32, ruby 2.7.6-138.module+el8.6.0+16148+54b2ba8f, ruby 3.0.4-141.module+el8.6.0+16311+3e5e17e9, rubygem-pg 1.0.0-2.module+el8.1.0+3656+f80bfa1d, rubygem-pg 1.1.4-1.module+el8.1.0+3653+beb38eb0, +85 more
    fixed: vendor fix RHSA-2022:0543
  • 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 Enterprise Linux AppStream EUS (v.8.4) ruby 2.6.9-108.module+el8.4.0+14070+b3717926, rubygem-pg 1.1.4-1.module+el8.1.0+3653+beb38eb0, ruby-libs 2.6.9-108.module+el8.4.0+14070+b3717926, 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-2022:0544
  • Red Hat Software Collections for RHEL Workstation(v. 7) rh-ruby26-ruby 2.6.9-120.el7, rh-ruby27-ruby 2.7.6-131.el7, rh-ruby30-ruby 3.0.4-149.el7, rh-ruby27-rubygems 3.1.6-131.el7, rh-ruby26-ruby-libs 2.6.9-120.el7, rh-ruby27-ruby-libs 2.7.6-131.el7, +49 more Red Hat Software Collections for RHEL(v. 7) rh-ruby26-ruby 2.6.9-120.el7, rh-ruby27-ruby 2.7.6-131.el7, rh-ruby30-ruby 3.0.4-149.el7, rh-ruby27-rubygems 3.1.6-131.el7, rh-ruby26-ruby-libs 2.6.9-120.el7, rh-ruby27-ruby-libs 2.7.6-131.el7, +49 more
    fixed: vendor fix RHSA-2022:0708
  • Red Hat Enterprise Linux 9 ruby, rubygems, ruby-libs, rubygem-irb, rubygem-rbs, rubygem-rss, +13 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

3.46% chance of exploitation in the next 30 days, higher than 89% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • ruby-lang.org https://www.ruby-lang.org/en/news/2021/11/15/date-parsing-method-regexp-dos-cve-2021-41817/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P
OSV 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
rubygems date
>=3.2.0, <3.2.1
>=3.1.0, <3.1.2
>=3.0.0, <3.0.2
<2.0.1
3.2.1
3.1.2
3.0.2
2.0.1
bitnami ruby
>=2.6.0, <2.6.9
>=2.7.0, <2.7.5
>=3.0.0, <3.0.3
2.6.9
2.7.5
3.0.3
bitnami ruby-min
>=2.6.0, <2.6.9
>=2.7.0, <2.7.5
>=3.0.0, <3.0.3
2.6.9
2.7.5
3.0.3
julia ruby_jll
all versions
 no fix listed

Classification

Weakness
  • CWE-1333 Inefficient Regular Expression Complexity

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.