CVE-2026-93471 (GCVE-0-2026-93471)

Vulnerability from cvelistv5 – Published: 2026-10-22 06:59 – Updated: 2026-10-22 06:59
VLAI
Title
Unbounded SAML message decompression in esaml allows memory exhaustion
Summary
Improper Handling of Highly Compressed Data (Data Amplification) in esaml_binding in dropbox esaml allows an unauthenticated attacker to exhaust server memory and crash the Erlang VM via a crafted compressed SAMLResponse. esaml_binding:decode_response/2 base64-decodes the attacker-supplied SAMLResponse, inflates it with zlib:unzip/1 with no bound on the output, then converts the result to a charlist with binary_to_list/1 before parsing. This runs on the SAML consume (ACS) and single-logout endpoints, which accept unauthenticated requests by design, and it runs before any signature check. A small deflate stream reaches a compression ratio near 1000 to 1, so a request body of tens of kilobytes inflates to hundreds of megabytes and then to several gigabytes of list heap, so a few requests exhaust memory and take the node down. This issue affects esaml: from 0.1.0 onward.
CWE
  • CWE-409 - Improper Handling of Highly Compressed Data (Data Amplification)
Assigner
EEF CNA under the mitre root
CNA scorecard A 96/100 over 318 records in the last 180 days details
Impacted products
Vendor Product Version CPE status
handnot2 esaml Affected: deeb84378d5c82153b470e99d24f77c38afca14a , < * (git)
    cpe:2.3:a:handnot2:esaml:*:*:*:*:*:*:*:*
Create a notification for this product.
arekinath esaml Affected: deeb84378d5c82153b470e99d24f77c38afca14a , < * (git)
    cpe:2.3:a:arekinath:esaml:*:*:*:*:*:*:*:*
Create a notification for this product.
dropbox esaml Affected: 0.1.0 , < * (semver)
    cpe:2.3:a:dropbox:esaml:*:*:*:*:*:*:*:*
Create a notification for this product.
dropbox esaml Affected: deeb84378d5c82153b470e99d24f77c38afca14a , < * (git)
    cpe:2.3:a:dropbox:esaml:*:*:*:*:*:*:*:*
Create a notification for this product.
Show details on NVD website

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                "collectionURL": "https://repo.hex.pm",
                "cpes": [
                  "cpe:2.3:a:dropbox:esaml:*:*:*:*:*:*:*:*"
                ],
                "defaultStatus": "unaffected",
                "modules": [
                  "esaml_binding",
                  "esaml_cowboy"
                ],
                "packageName": "esaml",
                "packageURL": "pkg:hex/esaml",
                "product": "esaml",
                "programFiles": [
                  "src/esaml_binding.erl",
                  "src/esaml_cowboy.erl"
                ],
                "programRoutines": [
                  {
                    "name": "esaml_binding:decode_response/2"
                  },
                  {
                    "name": "esaml_cowboy:validate_assertion/2"
                  },
                  {
                    "name": "esaml_cowboy:validate_logout/2"
                  }
                ],
                "repo": "https://github.com/dropbox/esaml",
                "vendor": "dropbox",
                "versions": [
                  {
                    "lessThan": "*",
                    "status": "affected",
                    "version": "0.1.0",
                    "versionType": "semver"
                  }
                ]
              },
              {
                "collectionURL": "https://github.com",
                "cpes": [
                  "cpe:2.3:a:dropbox:esaml:*:*:*:*:*:*:*:*"
                ],
                "defaultStatus": "unaffected",
                "modules": [
                  "esaml_binding",
                  "esaml_cowboy"
                ],
                "packageName": "dropbox/esaml",
                "packageURL": "pkg:github/dropbox/esaml",
                "product": "esaml",
                "programFiles": [
                  "src/esaml_binding.erl",
                  "src/esaml_cowboy.erl"
                ],
                "programRoutines": [
                  {
                    "name": "esaml_binding:decode_response/2"
                  },
                  {
                    "name": "esaml_cowboy:validate_assertion/2"
                  },
                  {
                    "name": "esaml_cowboy:validate_logout/2"
                  }
                ],
                "repo": "https://github.com/dropbox/esaml",
                "vendor": "dropbox",
                "versions": [
                  {
                    "lessThan": "*",
                    "status": "affected",
                    "version": "deeb84378d5c82153b470e99d24f77c38afca14a",
                    "versionType": "git"
                  }
                ]
              }
            ],
            "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "Improper Handling of Highly Compressed Data (Data Amplification) in esaml_binding in dropbox esaml allows an unauthenticated attacker to exhaust server memory and crash the Erlang VM via a crafted compressed SAMLResponse.\n\nesaml_binding:decode_response/2 base64-decodes the attacker-supplied SAMLResponse, inflates it with zlib:unzip/1 with no bound on the output, then converts the result to a charlist with binary_to_list/1 before parsing. This runs on the SAML consume (ACS) and single-logout endpoints, which accept unauthenticated requests by design, and it runs before any signature check. A small deflate stream reaches a compression ratio near 1000 to 1, so a request body of tens of kilobytes inflates to hundreds of megabytes and then to several gigabytes of list heap, so a few requests exhaust memory and take the node down.\n\nThis issue affects esaml: from 0.1.0 onward."
          }
        ],
        "id": "CVE-2026-93471",
        "lastModified": "2026-10-22T16:58:51.997",
        "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": "2026-10-22T09:17:16.827",
        "references": [
          {
            "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
            "url": "https://cna.erlef.org/cves/CVE-2026-93471.html"
          },
          {
            "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
            "url": "https://github.com/arekinath/esaml/commit/deeb84378d5c82153b470e99d24f77c38afca14a"
          },
          {
            "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
            "url": "https://github.com/dropbox/esaml/commit/deeb84378d5c82153b470e99d24f77c38afca14a"
          },
          {
            "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
            "url": "https://github.com/handnot2/esaml/commit/deeb84378d5c82153b470e99d24f77c38afca14a"
          },
          {
            "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
            "url": "https://osv.dev/vulnerability/EEF-CVE-2026-93471"
          }
        ],
        "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "vulnStatus": "Deferred",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-409"
              }
            ],
            "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
            "type": "Secondary"
          }
        ]
      }
    }
  }
}



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