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Vulnerability record · public intelligence
CVE-2021-33621
UNKNOWN

HTTP response splitting in CGI

Published Nov 18, 2022 · Updated Nov 3, 2026

Severity · CVSSUNKNOWN · Not scored
Known exploitationNot listed
EPSS / likelihood2.45%
QFinch risk scoreNot available

Original summary

Normalized public record · Updated Nov 3, 2026

HTTP response splitting in CGI

Publisher and source text is retained separately from QFinch interpretation.

QFinch assessment

Ruby gem cgi.rb prior to versions 0.3.5, 0.2.2 and 0.1.0.2 allow HTTP header injection. If a CGI application using the CGI library inserts untrusted input into the HTTP response header, an attacker can exploit it to insert a newline character to split a header, and inject malicious content to deceive clients. This issue has been patched in versions 0.3.5, 0.2.2 and 0.1.0.2.

Evidence: public source records

Affected products

Affected scope reported by the available public evidence
Affected package, product or rangeFix status
Consult the referenced vendor advisory for affected versions.Consult source advisory

Matching a version is only one part of assessing exposure. QFinch has not assessed your environment on this public page.

Remediation

Apply the vendor-supported fixed release or mitigation, then verify the affected component is no longer reachable.

  1. Confirm the affected product and reachable code path exist in your environment.
  2. Apply the vendor-supported patch or mitigation from the primary advisory.
  3. Rescan the exact deployed revision and retain verification evidence.
Review primary references

Evidence coverage

FIRST-EPSSCVE-LIST-V5
SSVC priority
MEDIUM
Confidence
Not available
Aliases
None reported

Scores appear only when corresponding evidence exists. Missing data is never interpreted as zero risk.

Sources and record history

  1. www.ruby-lang.org ↗
  2. FEDORA-2022-ef96a58bbe ↗
  3. FEDORA-2022-f0f6c6bec2 ↗
  4. FEDORA-2022-b9b710f199 ↗
  5. security.netapp.com ↗
  6. [debian-lts-announce] 20230609 [SECURITY] [DLA 3450-1] ruby2.5 security update ↗
  7. GLSA-202401-27 ↗
  8. lists.debian.org ↗

Record history

Published Nov 18, 2022 · Last refreshed Nov 3, 2026

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