Vulnerability-Lookup

CVE-2026-7790 (GCVE-0-2026-7790)

Vulnerability from cvelistv5 – Published: 2026-05-11 18:06 – Updated: 2026-05-26 19:46

Title

Unbounded chunk-size hex digits in cowlib cause quadratic CPU and memory DoS

Summary

Uncontrolled Resource Consumption vulnerability in ninenines cowlib (cow_http_te module) allows Excessive Allocation. The chunked transfer-encoding parser in cow_http_te accepts an unbounded number of hex digits in the chunk-size field. Each digit causes a bignum multiplication (Len * 16 + digit), so parsing N hex digits requires O(N²) CPU work and O(N) memory. Additionally, when input is drip-fed, the parser discards the accumulated length on each partial read and restarts from zero on resumption, raising the cost to O(N³). An unauthenticated remote attacker can exploit this by sending an HTTP/1.1 request with Transfer-Encoding: chunked and a very long chunk-size hex string to cause denial of service through CPU exhaustion and memory amplification. This vulnerability is associated with program file src/cow_http_te.erl and program routines cow_http_te:stream_chunked/2, cow_http_te:chunked_len/4. This issue affects cowlib: from 0.6.0 before 2.16.1.

Severity

8.7 (High)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CWE

CWE-400 - Uncontrolled Resource Consumption

Assigner

EEF

References

3 references

URL	Tags
https://cna.erlef.org/cves/CVE-2026-7790.html	relatedthird-party-advisory
https://osv.dev/vulnerability/EEF-CVE-2026-7790	related
https://github.com/ninenines/cowlib/commit/a4b803…	patch

Impacted products

2 products

Vendor	Product	Version
ninenines	cowlib	Affected: 0.6.0 , < 2.16.1 (semver) cpe:2.3:a:ninenines:cowlib::::::::
ninenines	cowlib	Affected: 8c0e428b012c59f553a264f285ed89d36f791e3e , < a4b8039ce8c93ab00867ef6b7e888822c09f4369 (git) cpe:2.3:a:ninenines:cowlib::::::::

Credits

Peter Ullrich Loïc Hoguin

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-7790

Vulnerability from fkie_nvd - Published: 2026-05-11 19:16 - Updated: 2026-05-13 15:57

Severity

8.7 (High) - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Summary

References

	URL	Tags
	6b3ad84c-e1a6-4bf7-a703-f496b71e49db	https://cna.erlef.org/cves/CVE-2026-7790.html
	6b3ad84c-e1a6-4bf7-a703-f496b71e49db	https://github.com/ninenines/cowlib/commit/a4b8039ce8c93ab00867ef6b7e888822c09f4369
	6b3ad84c-e1a6-4bf7-a703-f496b71e49db	https://osv.dev/vulnerability/EEF-CVE-2026-7790

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Uncontrolled Resource Consumption vulnerability in ninenines cowlib (cow_http_te module) allows Excessive Allocation.\n\nThe chunked transfer-encoding parser in cow_http_te accepts an unbounded number of hex digits in the chunk-size field. Each digit causes a bignum multiplication (Len * 16 + digit), so parsing N hex digits requires O(N\u00b2) CPU work and O(N) memory. Additionally, when input is drip-fed, the parser discards the accumulated length on each partial read and restarts from zero on resumption, raising the cost to O(N\u00b3). An unauthenticated remote attacker can exploit this by sending an HTTP/1.1 request with Transfer-Encoding: chunked and a very long chunk-size hex string to cause denial of service through CPU exhaustion and memory amplification.\n\nThis vulnerability is associated with program file src/cow_http_te.erl and program routines cow_http_te:stream_chunked/2, cow_http_te:chunked_len/4.\n\nThis issue affects cowlib: from 0.6.0 before 2.16.1."
    }
  ],
  "id": "CVE-2026-7790",
  "lastModified": "2026-05-13T15:57:03.607",
  "metrics": {
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 8.7,
          "baseSeverity": "HIGH",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "version": "4.0",
          "vulnAvailabilityImpact": "HIGH",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "NONE",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-05-11T19:16:29.477",
  "references": [
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://cna.erlef.org/cves/CVE-2026-7790.html"
    },
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://github.com/ninenines/cowlib/commit/a4b8039ce8c93ab00867ef6b7e888822c09f4369"
    },
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-7790"
    }
  ],
  "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
  "vulnStatus": "Undergoing Analysis",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-400"
        }
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "type": "Secondary"
    }
  ]
}

GHSA-32P9-57CR-4X65

Vulnerability from github – Published: 2026-05-11 21:31 – Updated: 2026-05-18 16:49

Summary

cowlib cow_http_te module: Uncontrolled Resource Consumption vulnerability allows Excessive Allocation

Details

Uncontrolled Resource Consumption vulnerability in ninenines cowlib (cow_http_te module) allows Excessive Allocation.

The chunked transfer-encoding parser in cow_http_te accepts an unbounded number of hex digits in the chunk-size field. Each digit causes a bignum multiplication (Len * 16 + digit), so parsing N hex digits requires O(N²) CPU work and O(N) memory. Additionally, when input is drip-fed, the parser discards the accumulated length on each partial read and restarts from zero on resumption, raising the cost to O(N³). An unauthenticated remote attacker can exploit this by sending an HTTP/1.1 request with Transfer-Encoding: chunked and a very long chunk-size hex string to cause denial of service through CPU exhaustion and memory amplification.

This vulnerability is associated with program file src/cow_http_te.erl and program routines cow_http_te:stream_chunked/2, cow_http_te:chunked_len/4.

This issue affects cowlib: from 0.6.0 before 2.16.1.

Severity

8.7 (High)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "Hex",
        "name": "cowlib"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.6.0"
            },
            {
              "fixed": "2.16.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-7790"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-18T16:49:21Z",
    "nvd_published_at": "2026-05-11T19:16:29Z",
    "severity": "HIGH"
  },
  "details": "Uncontrolled Resource Consumption vulnerability in ninenines cowlib (cow_http_te module) allows Excessive Allocation.\n\nThe chunked transfer-encoding parser in cow_http_te accepts an unbounded number of hex digits in the chunk-size field. Each digit causes a bignum multiplication (Len * 16 + digit), so parsing N hex digits requires O(N\u00b2) CPU work and O(N) memory. Additionally, when input is drip-fed, the parser discards the accumulated length on each partial read and restarts from zero on resumption, raising the cost to O(N\u00b3). An unauthenticated remote attacker can exploit this by sending an HTTP/1.1 request with Transfer-Encoding: chunked and a very long chunk-size hex string to cause denial of service through CPU exhaustion and memory amplification.\n\nThis vulnerability is associated with program file src/cow_http_te.erl and program routines cow_http_te:stream_chunked/2, cow_http_te:chunked_len/4.\n\nThis issue affects cowlib: from 0.6.0 before 2.16.1.",
  "id": "GHSA-32p9-57cr-4x65",
  "modified": "2026-05-18T16:49:21Z",
  "published": "2026-05-11T21:31:35Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-7790"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ninenines/cowlib/commit/a4b8039ce8c93ab00867ef6b7e888822c09f4369"
    },
    {
      "type": "WEB",
      "url": "https://cna.erlef.org/cves/CVE-2026-7790.html"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/ninenines/cowlib"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ninenines/cowlib/releases/tag/2.16.1"
    },
    {
      "type": "WEB",
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-7790"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": " cowlib cow_http_te module: Uncontrolled Resource Consumption vulnerability allows Excessive Allocation"
}

MSRC_CVE-2026-7790

Vulnerability from csaf_microsoft - Published: 2026-05-02 00:00 - Updated: 2026-05-26 01:38

Summary

Unbounded chunk-size hex digits in cowlib cause quadratic CPU and memory DoS

Notes

Additional Resources: To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle

Disclaimer: The information provided in the Microsoft Knowledge Base is provided \"as is\" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.

CVE-2026-7790

CWE-400 - Uncontrolled Resource Consumption

Affected products

Fixed 1 product

Product	Identifier	Version	Remediation
Unresolved product id: 20623-17084		—

Known affected 1 product

Product	Identifier	Version	Remediation
Unresolved product id: 17084-1		—	Vendor Fix fix

References

4 references

URL	Category
https://msrc.microsoft.com/csaf/vex/2026/msrc_cve…	self
https://support.microsoft.com/lifecycle	external
https://www.first.org/cvss	external
https://msrc.microsoft.com/csaf/vex/2026/msrc_cve…	self

JSON

To clipboard

{
  "document": {
    "category": "csaf_vex",
    "csaf_version": "2.0",
    "distribution": {
      "text": "Public",
      "tlp": {
        "label": "WHITE",
        "url": "https://www.first.org/tlp/"
      }
    },
    "lang": "en-US",
    "notes": [
      {
        "category": "general",
        "text": "To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle",
        "title": "Additional Resources"
      },
      {
        "category": "legal_disclaimer",
        "text": "The information provided in the Microsoft Knowledge Base is provided \\\"as is\\\" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.",
        "title": "Disclaimer"
      }
    ],
    "publisher": {
      "category": "vendor",
      "contact_details": "secure@microsoft.com",
      "name": "Microsoft Security Response Center",
      "namespace": "https://msrc.microsoft.com"
    },
    "references": [
      {
        "category": "self",
        "summary": "CVE-2026-7790 Unbounded chunk-size hex digits in cowlib cause quadratic CPU and memory DoS - VEX",
        "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-7790.json"
      },
      {
        "category": "external",
        "summary": "Microsoft Support Lifecycle",
        "url": "https://support.microsoft.com/lifecycle"
      },
      {
        "category": "external",
        "summary": "Common Vulnerability Scoring System",
        "url": "https://www.first.org/cvss"
      }
    ],
    "title": "Unbounded chunk-size hex digits in cowlib cause quadratic CPU and memory DoS",
    "tracking": {
      "current_release_date": "2026-05-26T01:38:25.000Z",
      "generator": {
        "date": "2026-05-26T07:13:49.449Z",
        "engine": {
          "name": "MSRC Generator",
          "version": "1.0"
        }
      },
      "id": "msrc_CVE-2026-7790",
      "initial_release_date": "2026-05-02T00:00:00.000Z",
      "revision_history": [
        {
          "date": "2026-05-15T01:02:37.000Z",
          "legacy_version": "1",
          "number": "1",
          "summary": "Information published."
        },
        {
          "date": "2026-05-26T01:38:25.000Z",
          "legacy_version": "2",
          "number": "2",
          "summary": "Information published."
        }
      ],
      "status": "final",
      "version": "2"
    }
  },
  "product_tree": {
    "branches": [
      {
        "branches": [
          {
            "branches": [
              {
                "category": "product_version",
                "name": "3.0",
                "product": {
                  "name": "Azure Linux 3.0",
                  "product_id": "17084"
                }
              }
            ],
            "category": "product_name",
            "name": "Azure Linux"
          },
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "\u003cazl3 rabbitmq-server 0:3.13.7-3.azl3",
                "product": {
                  "name": "\u003cazl3 rabbitmq-server 0:3.13.7-3.azl3",
                  "product_id": "1"
                }
              },
              {
                "category": "product_version",
                "name": "azl3 rabbitmq-server 0:3.13.7-3.azl3",
                "product": {
                  "name": "azl3 rabbitmq-server 0:3.13.7-3.azl3",
                  "product_id": "20623"
                }
              }
            ],
            "category": "product_name",
            "name": "rabbitmq-server"
          }
        ],
        "category": "vendor",
        "name": "Microsoft"
      }
    ],
    "relationships": [
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "\u003cazl3 rabbitmq-server 0:3.13.7-3.azl3 as a component of Azure Linux 3.0",
          "product_id": "17084-1"
        },
        "product_reference": "1",
        "relates_to_product_reference": "17084"
      },
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "azl3 rabbitmq-server 0:3.13.7-3.azl3 as a component of Azure Linux 3.0",
          "product_id": "20623-17084"
        },
        "product_reference": "20623",
        "relates_to_product_reference": "17084"
      }
    ]
  },
  "vulnerabilities": [
    {
      "cve": "CVE-2026-7790",
      "cwe": {
        "id": "CWE-400",
        "name": "Uncontrolled Resource Consumption"
      },
      "notes": [
        {
          "category": "general",
          "text": "EEF",
          "title": "Assigning CNA"
        }
      ],
      "product_status": {
        "fixed": [
          "20623-17084"
        ],
        "known_affected": [
          "17084-1"
        ]
      },
      "references": [
        {
          "category": "self",
          "summary": "CVE-2026-7790 Unbounded chunk-size hex digits in cowlib cause quadratic CPU and memory DoS - VEX",
          "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-7790.json"
        }
      ],
      "remediations": [
        {
          "category": "vendor_fix",
          "date": "2026-05-15T01:02:37.000Z",
          "details": "0:3.13.7-4.azl3:Security Update:https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade",
          "product_ids": [
            "17084-1"
          ],
          "url": "https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade"
        }
      ],
      "title": "Unbounded chunk-size hex digits in cowlib cause quadratic CPU and memory DoS"
    }
  ]
}

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.

Action not permitted

CVE-2026-7790 (GCVE-0-2026-7790)

FKIE_CVE-2026-7790

GHSA-32P9-57CR-4X65

MSRC_CVE-2026-7790

Tags

Sightings

Nomenclature