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No exploitation reportedFix available

CVE-2021-41819

No exploitation reported by the sources we read.

  • Published2022-01-01
  • Fixed in0.3.1 · 0.2.1 · 0.1.0.1
  • WeaknessCWE-565

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

CGI::Cookie.parse in Ruby through 2.6.8 mishandles security prefixes in cookie names. This also affects the CGI gem through 0.3.0 for Ruby.

Timeline

dates in UTC
  1. 2022-01-0106:15CVE publishedNVD

Versions per branch

OSV · NVD
cgi
BranchAffectedFixed in
0.3≥ 0.3.0, < 0.3.10.3.1
0.2≥ 0.2.0, < 0.2.10.2.1
0.1< 0.1.0.10.1.0.1
Ruby
BranchAffectedFixed in
3.0≥ 3.0.0, < 3.0.33.0.3
2.7≥ 2.7.0, < 2.7.52.7.5
2.6< 2.6.92.6.9
2.6≤ 2.6.8no fix published
Debian debian linux
BranchAffectedFixed in
9.0= 9.0no fix published
10.0= 10.0no fix published
11.0= 11.0no fix published

7 more products in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • rh-ruby26-rubyRed Hat:rhel_software_collections:3::el7all versions · fixed in 0:2.6.9-120.el7and 4 other packages
  • rh-ruby26-rubygem-bigdecimalRed Hat:rhel_software_collections:3::el7all versions · fixed in 0:1.4.1-120.el7
  • rh-ruby26-rubygem-bundlerRed Hat:rhel_software_collections:3::el7all versions · fixed in 0:1.17.2-120.el7
  • rh-ruby26-rubygem-did_you_meanRed Hat:rhel_software_collections:3::el7all versions · fixed in 0:1.3.0-120.el7
  • rh-ruby26-rubygem-io-consoleRed Hat:rhel_software_collections:3::el7all versions · fixed in 0:0.4.7-120.el7
  • rh-ruby26-rubygem-irbRed Hat:rhel_software_collections:3::el7all versions · fixed in 0:1.0.0-120.el7
  • rh-ruby26-rubygem-jsonRed Hat:rhel_software_collections:3::el7all versions · fixed in 0:2.1.0-120.el7
  • rh-ruby26-rubygem-minitestRed Hat:rhel_software_collections:3::el7all versions · fixed in 0:5.11.3-120.el7

402 more package ranges on OSV.dev

Vendor advisories

  • CVE-2021-41819 Red Hat Product Security1,127 products fixed · 26 known affected

    ruby: Cookie prefix spoofing in CGI::Cookie.parse

    ruby as a component of Red Hat Enterprise Linux 6 · ruby-devel as a component of Red Hat Enterprise Linux 6 · ruby-docs as a component of Red Hat Enterprise Linux 6 · +23 more

  • RHSA-2026:8838 Red Hat Product Security13 products fixed

    Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update

  • RHSA-2026:7307 Red Hat Product Security13 products fixed

    Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update

  • RHSA-2026:7305 Red Hat Product Security13 products fixed

    Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update

  • RHSA-2022:6856 Red Hat Product Security68 products fixed

    Red Hat Security Advisory: rh-ruby27-ruby security, bug fix, and enhancement update

  • RHSA-2022:6855 Red Hat Product Security62 products fixed

    Red Hat Security Advisory: rh-ruby30-ruby security, bug fix, and enhancement update

8 more advisories

Full record on NVD

Fix

  1. Update cgi to 0.3.1 · 0.2.1 · 0.1.0.1
  2. Vendor fix Red Hat Product Security RHSA-2026:8838 · 13 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
  3. Vendor fix Red Hat Product Security RHSA-2022:6856 · 68 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Published
2022-01-01
Last Modified
2026-06-17
NVD status
Modified
GitHub Advisory
GHSA-4vf4-qmvg-mh7h

Frequently asked questions

What is CVE-2021-41819?

CGI::Cookie.parse in Ruby through 2.6.8 mishandles security prefixes in cookie names. This also affects the CGI gem through 0.3.0 for Ruby.

Is CVE-2021-41819 actively exploited?

Active exploitation of CVE-2021-41819 has not been confirmed. Its EPSS score was 3.2% on 2026-11-09, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-41819?

CVE-2021-41819 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.

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Sources for this record