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BREW-PGSLICE-CVE-2021-33621 (GHSA-VC47-6RQG-C7F5)

Vulnerability from osv_homebrew – Published: 2026-08-13 17:26 – Updated: 2026-08-13 17:26 – Source website
VLAI
Summary
HTTP response splitting in CGI
Details

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.

Severity
8.8 (High)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "fix": "bump",
        "range_state": "fixed",
        "resource": "cgi",
        "resource_purl": "pkg:gem/cgi@0.5.1",
        "upstream_fixed_in": "0.3.5"
      },
      "package": {
        "ecosystem": "Homebrew",
        "name": "pgslice",
        "purl": "pkg:brew/pgslice"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.7.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "confidence": "high",
    "source": "matched",
    "strategy": "registry",
    "upstream_evidence": [
      {
        "ecosystem": "RubyGems",
        "key": "pkg:gem/cgi@0.5.1",
        "name": "cgi",
        "resource": "cgi",
        "strategy": "registry",
        "subject_version": "0.5.1"
      }
    ]
  },
  "details": "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.",
  "id": "BREW-pgslice-CVE-2021-33621",
  "modified": "2026-08-13T17:26:07Z",
  "published": "2026-08-13T17:26:07Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-33621"
    },
    {
      "type": "WEB",
      "url": "https://hackerone.com/reports/1204695"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/cgi/CVE-2021-33621.yml"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2023/06/msg00012.html"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2024/09/msg00000.html"
    },
    {
      "type": "WEB",
      "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/DQR7LWED6VAPD5ATYOBZIGJQPCUBRJBX"
    },
    {
      "type": "WEB",
      "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/THVTYHHEOVLQFCFHWURZYO7PVUPBHRZD"
    },
    {
      "type": "WEB",
      "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/YACE6ORF2QBXXBK2V2CM36D7TZMEJVAS"
    },
    {
      "type": "WEB",
      "url": "https://security.gentoo.org/glsa/202401-27"
    },
    {
      "type": "WEB",
      "url": "https://security.netapp.com/advisory/ntap-20221228-0004"
    },
    {
      "type": "WEB",
      "url": "https://www.ruby-lang.org/en/news/2022/11/22/http-response-splitting-in-cgi-cve-2021-33621"
    }
  ],
  "schema_version": "1.7.3",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "HTTP response splitting in CGI",
  "upstream": [
    "GHSA-vc47-6rqg-c7f5",
    "BIT-ruby-2021-33621",
    "BIT-ruby-min-2021-33621",
    "CVE-2021-33621"
  ]
}



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