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Security advisory

Type: advisorySources: OSVCVE: CVE-2020-4054

In Sanitize (RubyGem sanitize) greater than or equal to 3.0.0 and less than 5.2.1, there is a cross-site scripting vulnerability. When HTML is sanitized using Sanitize's "relaxed" config, or a custom config that allows certain elements, some content in a math or svg element may not be sanitized correctly even if math and svg are not in the allowlist. You are likely to be vulnerable to this issue if you use Sanitize's relaxed config or a custom config that allows one or more of the following HTML elements: iframe, math, noembed, noframes, noscript, plaintext, script, style, svg, xmp. Using carefully crafted input, an attacker may be able to sneak arbitrary HTML through Sanitize, potentially resulting in XSS (cross-site scripting) or other undesired behavior when that HTML is rendered in a browser. This has been fixed in 5.2.1.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2020-4054
Confirmed fixed CVEs
Not specified
Updated in this feed
31 Oct 2026, 11:13 UTC · Revision 1

Source evidence

CVE-2020-4054

core-osv · Original source

Published 16 Jun 2020, 22:15 UTC

In Sanitize (RubyGem sanitize) greater than or equal to 3.0.0 and less than 5.2.1, there is a cross-site scripting vulnerability. When HTML is sanitized using Sanitize's "relaxed" config, or a custom config that allows certain elements, some content in a math or svg element may not be sanitized correctly even if math and svg are not in the allowlist. You are likely to be vulnerable to this issue if you use Sanitize's relaxed config or a custom config that allows one or more of the following HTML elements: iframe, math, noembed, noframes, noscript, plaintext, script, style, svg, xmp. Using carefully crafted input, an attacker may be able to sneak arbitrary HTML through Sanitize, potentially resulting in XSS (cross-site scripting) or other undesired behavior when that HTML is rendered in a browser. This has been fixed in 5.2.1.

osv:CVE-2020-4054
Complete source record
{
  "id": "4d384a19c52809c64a657b6be13b3a9bc6666a4589ff672ec73a57cd5760c3a6",
  "url": "https://osv.dev/vulnerability/CVE-2020-4054",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2020-4054",
    "summary": "In Sanitize (RubyGem sanitize) greater than or equal to 3.0.0 and less than 5.2.1, there is a cross-site scripting vulnerability. When HTML is sanitized using Sanitize's \"relaxed\" config, or a custom config that allows certain elements, some content in a math or svg element may not be sanitized correctly even if math and svg are not in the allowlist. You are likely to be vulnerable to this issue if you use Sanitize's relaxed config or a custom config that allows one or more of the following HTML elements: iframe, math, noembed, noframes, noscript, plaintext, script, style, svg, xmp. Using carefully crafted input, an attacker may be able to sneak arbitrary HTML through Sanitize, potentially resulting in XSS (cross-site scripting) or other undesired behavior when that HTML is rendered in a browser. This has been fixed in 5.2.1.",
    "evidence": "osv:CVE-2020-4054",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2020-4054",
      "aliases": [
        "CVE-2020-4054",
        "GHSA-p4x4-rw2p-8j8m"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/rgrove/sanitize",
              "type": "GIT",
              "events": [
                {
                  "introduced": "3b68765f21c7387fa6ee0d348a40f7d4d4e94f21"
                },
                {
                  "fixed": "773d1af976b0e67a966bd3676ebab4f037395699"
                },
                {
                  "fixed": "a11498de9e283cd457b35ee252983662f7452aa9"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:sanitize_project:sanitize:*:*:*:*:*:ruby:*:*",
                    "range": [
                      {
                        "introduced": "3.0.0"
                      },
                      {
                        "fixed": "5.2.1"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "a11498de9e283cd457b35ee252983662f7452aa9"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "773d1af976b0e67a966bd3676ebab4f037395699"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v5.2.1"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v5.2.0",
            "v5.1.0",
            "v5.0.0",
            "v4.6.6",
            "v4.6.5",
            "v4.6.4",
            "v4.6.3",
            "v4.6.2",
            "v4.6.1",
            "v4.6.0",
            "v4.5.0",
            "v4.4.0",
            "v4.3.0",
            "v4.2.0",
            "v4.1.0",
            "v4.0.1",
            "v4.0.0",
            "v3.1.2",
            "v3.1.1",
            "v3.1.0",
            "v3.0.2",
            "v3.0.1",
            "v3.0.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2020-4054.json"
          }
        }
      ],
      "modified": "2026-10-20T10:53:28.180798875Z",
      "provider": "osv",
      "references": [
        "https://usn.ubuntu.com/4543-1/",
        "https://github.com/rgrove/sanitize/releases/tag/v5.2.1",
        "https://github.com/rgrove/sanitize/security/advisories/GHSA-p4x4-rw2p-8j8m",
        "https://www.debian.org/security/2020/dsa-4730",
        "https://github.com/rgrove/sanitize/commit/a11498de9e283cd457b35ee252983662f7452aa9"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2020-4054",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 384333,
  "published_at": "2020-06-16T22:15:10.693+00:00"
}