CVE-2026-109821

Full vulnerability record from the local CVENow database.

Description

Improper Validation of Specified Quantity in Input vulnerability in the Elixir standard library's URI module allows an attacker who supplies a URL to cause a denial of service through CPU exhaustion. URI.parse/1 converts the port component with String.to_integer/1 in split_authority/1 (lib/elixir/lib/uri.ex) without bounding its length, so a port of up to 1,262,592 decimal digits produces a bignum of that size and a longer one raises SystemLimitError. Rendering the parsed URI back to text (URI.to_string/1, inspect/1, logging, error formatting) converts the bignum with :erlang.integer_to_binary/1, which is quadratic on Erlang/OTP 27, 28 and 29.0: a 400,000-digit port renders in about 2.6 seconds and a 1 MB port in about 18 seconds. Ports above 65535 are also accepted. This issue affects elixir: from 0.5.0 before 1.18.6, from 1.19.0-rc.0 before 1.19.7, and from 1.20.0-rc.0 before 1.20.5.

Severity

MEDIUM

CVSS score

6.3 (v4.0)

Vulnerability status

Received

Source identifier

6b3ad84c-e1a6-4bf7-a703-f496b71e49db

Published

2026-10-30 09:17:12.143000

Last modified

2026-10-30 09:17:12.143000

View original CVE JSON

{
  "id": "CVE-2026-109821",
  "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
  "published": "2026-10-30T09:17:12.143",
  "lastModified": "2026-10-30T09:17:12.143",
  "vulnStatus": "Received",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Improper Validation of Specified Quantity in Input vulnerability in the Elixir standard library's URI module allows an attacker who supplies a URL to cause a denial of service through CPU exhaustion.\n\nURI.parse/1 converts the port component with String.to_integer/1 in split_authority/1 (lib/elixir/lib/uri.ex) without bounding its length, so a port of up to 1,262,592 decimal digits produces a bignum of that size and a longer one raises SystemLimitError. Rendering the parsed URI back to text (URI.to_string/1, inspect/1, logging, error formatting) converts the bignum with :erlang.integer_to_binary/1, which is quadratic on Erlang/OTP 27, 28 and 29.0: a 400,000-digit port renders in about 2.6 seconds and a 1 MB port in about 18 seconds. Ports above 65535 are also accepted.\n\nThis issue affects elixir: from 0.5.0 before 1.18.6, from 1.19.0-rc.0 before 1.19.7, and from 1.20.0-rc.0 before 1.20.5."
    }
  ],
  "affected": [
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "affectedData": [
        {
          "vendor": "elixir-lang",
          "product": "elixir",
          "defaultStatus": "unaffected",
          "packageName": "elixir",
          "cpes": [
            "cpe:2.3:a:elixir-lang:elixir:*:*:*:*:*:*:*:*"
          ],
          "modules": [
            "'Elixir.URI'",
            "'Elixir.String.Chars.URI'"
          ],
          "programFiles": [
            "lib/uri.ex"
          ],
          "programRoutines": [
            {
              "name": "'Elixir.URI':parse/1"
            },
            {
              "name": "'Elixir.URI':split_authority/1"
            },
            {
              "name": "'Elixir.URI':merge/2"
            },
            {
              "name": "'Elixir.URI':to_string/1"
            },
            {
              "name": "'Elixir.String.Chars.URI':to_string/1"
            }
          ],
          "repo": "https://github.com/elixir-lang/elixir",
          "packageURL": "pkg:otp/elixir?repository_url=https:%2F%2Fgithub.com%2Felixir-lang%2Felixir&vcs_url=git%2Bhttps:%2F%2Fgithub.com%2Felixir-lang%2Felixir.git",
          "versions": [
            {
              "version": "0.5.0",
              "lessThan": "1.18.6",
              "versionType": "semver",
              "status": "affected"
            },
            {
              "version": "1.19.0-rc.0",
              "lessThan": "1.19.7",
              "versionType": "semver",
              "status": "affected"
            },
            {
              "version": "1.20.0-rc.0",
              "lessThan": "1.20.5",
              "versionType": "semver",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "elixir-lang",
          "product": "elixir",
          "defaultStatus": "unaffected",
          "collectionURL": "https://github.com",
          "packageName": "elixir-lang/elixir",
          "cpes": [
            "cpe:2.3:a:elixir-lang:elixir:*:*:*:*:*:*:*:*"
          ],
          "modules": [
            "'Elixir.URI'",
            "'Elixir.String.Chars.URI'"
          ],
          "programFiles": [
            "lib/elixir/lib/uri.ex"
          ],
          "programRoutines": [
            {
              "name": "'Elixir.URI':parse/1"
            },
            {
              "name": "'Elixir.URI':split_authority/1"
            },
            {
              "name": "'Elixir.URI':merge/2"
            },
            {
              "name": "'Elixir.URI':to_string/1"
            },
            {
              "name": "'Elixir.String.Chars.URI':to_string/1"
            }
          ],
          "repo": "https://github.com/elixir-lang/elixir",
          "packageURL": "pkg:github/elixir-lang/elixir",
          "versions": [
            {
              "version": "39801821eef2d06524e5ebf5a0e4b3c380ad23ae",
              "lessThan": "*",
              "versionType": "git",
              "status": "affected",
              "changes": [
                {
                  "at": "9a39d64a4473d02681c486bc70681c972479d32b",
                  "status": "unaffected"
                },
                {
                  "at": "b70f33a591b6ab8eb0fa4a7e00bac1c2ed4e0d58",
                  "status": "unaffected"
                },
                {
                  "at": "07d9abc3f3ac4c8d2ba8384bd102b6d6205b08b7",
                  "status": "unaffected"
                },
                {
                  "at": "d879b39d778fec2f475689573d5672720c4f2a21",
                  "status": "unaffected"
                }
              ]
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV40": [
      {
        "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "type": "Secondary",
        "cvssData": {
          "version": "4.0",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/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",
          "baseScore": 6.3,
          "baseSeverity": "MEDIUM",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "attackRequirements": "PRESENT",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "NONE",
          "vulnAvailabilityImpact": "LOW",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "subAvailabilityImpact": "NONE",
          "exploitMaturity": "NOT_DEFINED",
          "confidentialityRequirement": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "availabilityRequirement": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "valueDensity": "NOT_DEFINED",
          "vulnerabilityResponseEffort": "NOT_DEFINED",
          "providerUrgency": "NOT_DEFINED"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-400"
        },
        {
          "lang": "en",
          "value": "CWE-1284"
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://cna.erlef.org/cves/CVE-2026-109821.html",
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://github.com/elixir-lang/elixir/commit/07d9abc3f3ac4c8d2ba8384bd102b6d6205b08b7",
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://github.com/elixir-lang/elixir/commit/39801821eef2d06524e5ebf5a0e4b3c380ad23ae",
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://github.com/elixir-lang/elixir/commit/9a39d64a4473d02681c486bc70681c972479d32b",
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://github.com/elixir-lang/elixir/commit/b70f33a591b6ab8eb0fa4a7e00bac1c2ed4e0d58",
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://github.com/elixir-lang/elixir/commit/d879b39d778fec2f475689573d5672720c4f2a21",
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://github.com/elixir-lang/elixir/security/advisories/GHSA-327h-97cv-59xg",
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://github.com/erlang/otp/security/advisories/GHSA-8qw4-2chm-mvj2",
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-109821",
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    }
  ]
}