CVE-2026-34829 (GCVE-0-2026-34829)

Vulnerability from cvelistv5 – Published: 2026-04-02 16:46 – Updated: 2026-06-30 12:09
VLAI
Title
Rack: Denial of Service via Unbounded Multipart File Upload Without Content-Length
Summary
Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Multipart::Parser only wraps the request body in a BoundedIO when CONTENT_LENGTH is present. When a multipart/form-data request is sent without a Content-Length header, such as with HTTP chunked transfer encoding, multipart parsing continues until end-of-stream with no total size limit. For file parts, the uploaded body is written directly to a temporary file on disk rather than being constrained by the buffered in-memory upload limit. An unauthenticated attacker can therefore stream an arbitrarily large multipart file upload and consume unbounded disk space. This results in a denial of service condition for Rack applications that accept multipart form data. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC
Exploitation: none Automatable: yes Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
  • CWE-400 - Uncontrolled Resource Consumption
  • CWE-770 - Allocation of Resources Without Limits or Throttling
Assigner
References
Impacted products
Vendor Product Version
rack rack Affected: < 2.2.23
Affected: >= 3.0.0.beta1, < 3.1.21
Affected: >= 3.2.0, < 3.2.6
Create a notification for this product.
Red Hat Logging Subsystem for Red Hat OpenShift     cpe:/a:redhat:logging:5
 Create a notification for this product.
Red Hat Red Hat 3scale API Management Platform 2     cpe:/a:redhat:red_hat_3scale_amp:2
 Create a notification for this product.
Red Hat Red Hat Enterprise Linux 10     cpe:/o:redhat:enterprise_linux:10
 Create a notification for this product.
Red Hat Red Hat Enterprise Linux 7     cpe:/o:redhat:enterprise_linux:7
 Create a notification for this product.
Red Hat Red Hat Enterprise Linux 8     cpe:/o:redhat:enterprise_linux:8
 Create a notification for this product.
Red Hat Red Hat Enterprise Linux 9     cpe:/o:redhat:enterprise_linux:9
 Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-34829",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-04-02T17:41:27.704414Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-04-02T17:41:33.990Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      },
      {
        "affected": [
          {
            "cpes": [
              "cpe:/a:redhat:logging:5"
            ],
            "defaultStatus": "affected",
            "product": "Logging Subsystem for Red Hat OpenShift",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/a:redhat:red_hat_3scale_amp:2"
            ],
            "defaultStatus": "affected",
            "product": "Red Hat 3scale API Management Platform 2",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/o:redhat:enterprise_linux:10"
            ],
            "defaultStatus": "unaffected",
            "product": "Red Hat Enterprise Linux 10",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/o:redhat:enterprise_linux:7"
            ],
            "defaultStatus": "unaffected",
            "product": "Red Hat Enterprise Linux 7",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/o:redhat:enterprise_linux:8"
            ],
            "defaultStatus": "unaffected",
            "product": "Red Hat Enterprise Linux 8",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/o:redhat:enterprise_linux:9"
            ],
            "defaultStatus": "unaffected",
            "product": "Red Hat Enterprise Linux 9",
            "vendor": "Red Hat"
          }
        ],
        "datePublic": "2026-04-02T16:46:47.357Z",
        "descriptions": [
          {
            "lang": "en",
            "value": "A flaw was found in Rack. An unauthenticated attacker can exploit this by sending a multipart/form-data request without a Content-Length header. This allows multipart parsing to continue without a total size limit, writing uploaded file parts directly to temporary files on disk. This unbounded disk space consumption leads to a Denial of Service (DoS) condition for Rack applications that accept multipart form data."
          }
        ],
        "metrics": [
          {
            "other": {
              "content": {
                "namespace": "https://access.redhat.com/security/updates/classification/",
                "value": "Important"
              },
              "type": "Red Hat severity rating"
            }
          },
          {
            "cvssV3_1": {
              "attackComplexity": "LOW",
              "attackVector": "NETWORK",
              "availabilityImpact": "HIGH",
              "baseScore": 7.5,
              "baseSeverity": "HIGH",
              "confidentialityImpact": "NONE",
              "integrityImpact": "NONE",
              "privilegesRequired": "NONE",
              "scope": "UNCHANGED",
              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
              "version": "3.1"
            },
            "format": "CVSS"
          }
        ],
        "problemTypes": [
          {
            "descriptions": [
              {
                "cweId": "CWE-770",
                "description": "Allocation of Resources Without Limits or Throttling",
                "lang": "en",
                "type": "CWE"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-06-30T12:09:07.377Z",
          "orgId": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
          "shortName": "redhat-SADP"
        },
        "references": [
          {
            "tags": [
              "vdb-entry",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/security/cve/CVE-2026-34829"
          },
          {
            "name": "RHBZ#2454488",
            "tags": [
              "issue-tracking",
              "x_refsource_REDHAT"
            ],
            "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2454488"
          },
          {
            "tags": [
              "x_sadp-csaf-vex"
            ],
            "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-34829.json"
          }
        ],
        "timeline": [
          {
            "lang": "en",
            "time": "2026-04-02T18:01:19.914Z",
            "value": "Reported to Red Hat."
          },
          {
            "lang": "en",
            "time": "2026-04-02T16:46:47.357Z",
            "value": "Made public."
          }
        ],
        "title": "rack: Rack: Denial of Service via unbounded multipart file upload",
        "workarounds": [
          {
            "lang": "en",
            "value": "Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability."
          }
        ],
        "x_adpType": "supplier",
        "x_generator": {
          "engine": "sadp-cli 1.0.0"
        }
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "rack",
          "vendor": "rack",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 2.2.23"
            },
            {
              "status": "affected",
              "version": "\u003e= 3.0.0.beta1, \u003c 3.1.21"
            },
            {
              "status": "affected",
              "version": "\u003e= 3.2.0, \u003c 3.2.6"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Multipart::Parser only wraps the request body in a BoundedIO when CONTENT_LENGTH is present. When a multipart/form-data request is sent without a Content-Length header, such as with HTTP chunked transfer encoding, multipart parsing continues until end-of-stream with no total size limit. For file parts, the uploaded body is written directly to a temporary file on disk rather than being constrained by the buffered in-memory upload limit. An unauthenticated attacker can therefore stream an arbitrarily large multipart file upload and consume unbounded disk space. This results in a denial of service condition for Rack applications that accept multipart form data. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-400",
              "description": "CWE-400: Uncontrolled Resource Consumption",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-770",
              "description": "CWE-770: Allocation of Resources Without Limits or Throttling",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-02T16:46:47.357Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/rack/rack/security/advisories/GHSA-8vqr-qjwx-82mw",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/rack/rack/security/advisories/GHSA-8vqr-qjwx-82mw"
        }
      ],
      "source": {
        "advisory": "GHSA-8vqr-qjwx-82mw",
        "discovery": "UNKNOWN"
      },
      "title": "Rack: Denial of Service via Unbounded Multipart File Upload Without Content-Length"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-34829",
    "datePublished": "2026-04-02T16:46:47.357Z",
    "dateReserved": "2026-03-30T20:52:53.284Z",
    "dateUpdated": "2026-06-30T12:09:07.377Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-34829",
      "date": "2026-07-06",
      "epss": "0.00369",
      "percentile": "0.28876"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-34829\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-04-02T17:16:26.103\",\"lastModified\":\"2026-06-30T03:18:59.300\",\"vulnStatus\":\"Modified\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Multipart::Parser only wraps the request body in a BoundedIO when CONTENT_LENGTH is present. When a multipart/form-data request is sent without a Content-Length header, such as with HTTP chunked transfer encoding, multipart parsing continues until end-of-stream with no total size limit. For file parts, the uploaded body is written directly to a temporary file on disk rather than being constrained by the buffered in-memory upload limit. An unauthenticated attacker can therefore stream an arbitrarily large multipart file upload and consume unbounded disk space. This results in a denial of service condition for Rack applications that accept multipart form data. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.\"}],\"affected\":[{\"source\":\"security-advisories@github.com\",\"affectedData\":[{\"vendor\":\"rack\",\"product\":\"rack\",\"versions\":[{\"version\":\"\u003c 2.2.23\",\"status\":\"affected\"},{\"version\":\"\u003e= 3.0.0.beta1, \u003c 3.1.21\",\"status\":\"affected\"},{\"version\":\"\u003e= 3.2.0, \u003c 3.2.6\",\"status\":\"affected\"}]}]},{\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\",\"affectedData\":[{\"vendor\":\"Red Hat\",\"product\":\"Logging Subsystem for Red Hat OpenShift\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/a:redhat:logging:5\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat 3scale API Management Platform 2\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/a:redhat:red_hat_3scale_amp:2\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat Enterprise Linux 10\",\"defaultStatus\":\"unaffected\",\"cpes\":[\"cpe:/o:redhat:enterprise_linux:10\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat Enterprise Linux 7\",\"defaultStatus\":\"unaffected\",\"cpes\":[\"cpe:/o:redhat:enterprise_linux:7\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat Enterprise Linux 8\",\"defaultStatus\":\"unaffected\",\"cpes\":[\"cpe:/o:redhat:enterprise_linux:8\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat Enterprise Linux 9\",\"defaultStatus\":\"unaffected\",\"cpes\":[\"cpe:/o:redhat:enterprise_linux:9\"]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":7.5,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":3.6},{\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":7.5,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":3.6}],\"ssvcV203\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"ssvcData\":{\"timestamp\":\"2026-04-02T17:41:27.704414Z\",\"id\":\"CVE-2026-34829\",\"options\":[{\"exploitation\":\"none\"},{\"automatable\":\"yes\"},{\"technicalImpact\":\"partial\"}],\"role\":\"CISA Coordinator\",\"version\":\"2.0.3\"}}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-400\"},{\"lang\":\"en\",\"value\":\"CWE-770\"}]},{\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-770\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:rack:rack:*:*:*:*:*:ruby:*:*\",\"versionEndExcluding\":\"2.2.23\",\"matchCriteriaId\":\"AD5DE7DE-3A8B-4064-A7D5-1E117A101E81\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:rack:rack:*:*:*:*:*:ruby:*:*\",\"versionStartIncluding\":\"3.0.0\",\"versionEndExcluding\":\"3.1.21\",\"matchCriteriaId\":\"6948AAA6-873D-46BA-AA22-4C81138128E1\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:rack:rack:*:*:*:*:*:ruby:*:*\",\"versionStartIncluding\":\"3.2.0\",\"versionEndExcluding\":\"3.2.6\",\"matchCriteriaId\":\"3FB592AD-E826-49BE-AC6D-E5F55FDCC96E\"}]}]}],\"references\":[{\"url\":\"https://github.com/rack/rack/security/advisories/GHSA-8vqr-qjwx-82mw\",\"source\":\"security-advisories@github.com\",\"tags\":[\"Vendor Advisory\"]},{\"url\":\"https://access.redhat.com/security/cve/CVE-2026-34829\",\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\"},{\"url\":\"https://bugzilla.redhat.com/show_bug.cgi?id=2454488\",\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\"},{\"url\":\"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-34829.json\",\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\"}]}}",
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-34829\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-04-02T17:41:27.704414Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-04-02T17:41:29.860Z\"}}], \"cna\": {\"title\": \"Rack: Denial of Service via Unbounded Multipart File Upload Without Content-Length\", \"source\": {\"advisory\": \"GHSA-8vqr-qjwx-82mw\", \"discovery\": \"UNKNOWN\"}, \"metrics\": [{\"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 7.5, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"HIGH\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\", \"integrityImpact\": \"NONE\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"availabilityImpact\": \"HIGH\", \"privilegesRequired\": \"NONE\", \"confidentialityImpact\": \"NONE\"}}], \"affected\": [{\"vendor\": \"rack\", \"product\": \"rack\", \"versions\": [{\"status\": \"affected\", \"version\": \"\u003c 2.2.23\"}, {\"status\": \"affected\", \"version\": \"\u003e= 3.0.0.beta1, \u003c 3.1.21\"}, {\"status\": \"affected\", \"version\": \"\u003e= 3.2.0, \u003c 3.2.6\"}]}], \"references\": [{\"url\": \"https://github.com/rack/rack/security/advisories/GHSA-8vqr-qjwx-82mw\", \"name\": \"https://github.com/rack/rack/security/advisories/GHSA-8vqr-qjwx-82mw\", \"tags\": [\"x_refsource_CONFIRM\"]}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Multipart::Parser only wraps the request body in a BoundedIO when CONTENT_LENGTH is present. When a multipart/form-data request is sent without a Content-Length header, such as with HTTP chunked transfer encoding, multipart parsing continues until end-of-stream with no total size limit. For file parts, the uploaded body is written directly to a temporary file on disk rather than being constrained by the buffered in-memory upload limit. An unauthenticated attacker can therefore stream an arbitrarily large multipart file upload and consume unbounded disk space. This results in a denial of service condition for Rack applications that accept multipart form data. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-400\", \"description\": \"CWE-400: Uncontrolled Resource Consumption\"}]}, {\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-770\", \"description\": \"CWE-770: Allocation of Resources Without Limits or Throttling\"}]}], \"providerMetadata\": {\"orgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"shortName\": \"GitHub_M\", \"dateUpdated\": \"2026-04-02T16:46:47.357Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-34829\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-04-02T17:41:33.990Z\", \"dateReserved\": \"2026-03-30T20:52:53.284Z\", \"assignerOrgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"datePublished\": \"2026-04-02T16:46:47.357Z\", \"assignerShortName\": \"GitHub_M\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.


Detection rules are retrieved from Rulezet.