Is CVE-2021-41819 in the CISA KEV catalog?

No. CVE-2021-41819 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-41819?

CVE-2021-41819 has a CVSS v3 base score of 7.5 (HIGH).

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

CVE-2021-41819 has an EPSS score of 2.93% (85th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-41819?

Upgrade ruby2.7 on debian 11 to 2.7.4-1+deb11u1 or later. Fixes are available for 12 affected products.

CVE & CISA-KEV Catalog

CVE-2021-41819

HIGHEPSS 85th pctl

7.5

CVSS v3

NVD

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.

CWE-565

How to fix

Remediation Available

ruby2.7Debian

Fixed in:2.7.4-1+deb11u1CVE-2021-41819

ruby4Rocky

Fixed in:0-main@noarchRHSA-2026:8838

Fixed in:0-main@x86_64RHSA-2026:8838

Fixed in:0-main@srcRHSA-2026:8838

Fixed in:0-main@aarch64RHSA-2026:8838

ruby4Red Hat / RHEL

Fixed in:0-main@x86_64RHSA-2026:8838

Fixed in:0-main@srcRHSA-2026:8838

Fixed in:0-main@aarch64RHSA-2026:8838

Fixed in:0-main@noarchRHSA-2026:8838

ruby2.3Ubuntu

Fixed in:2.3.1-2~ubuntu16.04.16+esm2USN-5235-1

ruby2.5Ubuntu

Fixed in:2.5.1-1ubuntu1.11USN-5235-1

ruby2.7Ubuntu

Fixed in:2.7.0-5ubuntu1.6USN-5235-1

Ruby 3.0Windows application

Affected:2.7.0 2.7.5Fixed in:2.7.5RubyInstaller Team

Affected:3.0.0 3.0.3Fixed in:3.0.3RubyInstaller Team

Ruby 3.1Windows application

Affected:3.0.0 3.0.3Fixed in:3.0.3RubyInstaller Team

Affected:2.7.0 2.7.5Fixed in:2.7.5RubyInstaller Team

Ruby 3.2Windows application

Affected:2.7.0 2.7.5Fixed in:2.7.5RubyInstaller Team

Affected:3.0.0 3.0.3Fixed in:3.0.3RubyInstaller Team

Ruby 3.2 with MSYS2Windows application

Affected:2.7.0 2.7.5Fixed in:2.7.5RubyInstaller Team

Affected:3.0.0 3.0.3Fixed in:3.0.3RubyInstaller Team

Ruby 3.3Windows application

Affected:2.7.0 2.7.5Fixed in:2.7.5RubyInstaller Team

Affected:3.0.0 3.0.3Fixed in:3.0.3RubyInstaller Team

Ruby 3.3 with MSYS2Windows application

Affected:3.0.0 3.0.3Fixed in:3.0.3RubyInstaller Team

Affected:2.7.0 2.7.5Fixed in:2.7.5RubyInstaller Team

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityHigh

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Exploit Intelligence

2.93%probability of exploitation in 30 days

85thpercentile

Elevated risk: more likely to be exploited than 85% of all known CVEs.

References

Exploit1

ruby-lang.org

Third-Party Advisory2

Other references3

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-05-22.