CVE-2026-93471
Full vulnerability record from the local CVENow database.
Description
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.
Severity
HIGH
CVSS score
8.7
(v4.0)
Vulnerability status
Deferred
Source identifier
6b3ad84c-e1a6-4bf7-a703-f496b71e49db
Published
2026-10-22 09:17:16.827000
Last modified
2026-10-22 16:58:51.997000
View original CVE JSON
{
"id": "CVE-2026-93471",
"sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"published": "2026-10-22T09:17:16.827",
"lastModified": "2026-10-22T16:58:51.997",
"vulnStatus": "Deferred",
"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."
}
],
"affected": [
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"affectedData": [
{
"vendor": "handnot2",
"product": "esaml",
"defaultStatus": "unaffected",
"collectionURL": "https://github.com",
"packageName": "handnot2/esaml",
"cpes": [
"cpe:2.3:a:handnot2:esaml:*:*:*:*:*:*:*:*"
],
"modules": [
"esaml_binding",
"esaml_cowboy"
],
"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/handnot2/esaml",
"packageURL": "pkg:github/handnot2/esaml",
"versions": [
{
"version": "deeb84378d5c82153b470e99d24f77c38afca14a",
"lessThan": "*",
"versionType": "git",
"status": "affected"
}
]
},
{
"vendor": "arekinath",
"product": "esaml",
"defaultStatus": "unaffected",
"collectionURL": "https://github.com",
"packageName": "arekinath/esaml",
"cpes": [
"cpe:2.3:a:arekinath:esaml:*:*:*:*:*:*:*:*"
],
"modules": [
"esaml_binding",
"esaml_cowboy"
],
"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/arekinath/esaml",
"packageURL": "pkg:github/arekinath/esaml",
"versions": [
{
"version": "deeb84378d5c82153b470e99d24f77c38afca14a",
"lessThan": "*",
"versionType": "git",
"status": "affected"
}
]
},
{
"vendor": "dropbox",
"product": "esaml",
"defaultStatus": "unaffected",
"collectionURL": "https://repo.hex.pm",
"packageName": "esaml",
"cpes": [
"cpe:2.3:a:dropbox:esaml:*:*:*:*:*:*:*:*"
],
"modules": [
"esaml_binding",
"esaml_cowboy"
],
"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",
"packageURL": "pkg:hex/esaml",
"versions": [
{
"version": "0.1.0",
"lessThan": "*",
"versionType": "semver",
"status": "affected"
}
]
},
{
"vendor": "dropbox",
"product": "esaml",
"defaultStatus": "unaffected",
"collectionURL": "https://github.com",
"packageName": "dropbox/esaml",
"cpes": [
"cpe:2.3:a:dropbox:esaml:*:*:*:*:*:*:*:*"
],
"modules": [
"esaml_binding",
"esaml_cowboy"
],
"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",
"packageURL": "pkg:github/dropbox/esaml",
"versions": [
{
"version": "deeb84378d5c82153b470e99d24f77c38afca14a",
"lessThan": "*",
"versionType": "git",
"status": "affected"
}
]
}
]
}
],
"metrics": {
"cvssMetricV40": [
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"type": "Secondary",
"cvssData": {
"version": "4.0",
"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",
"baseScore": 8.7,
"baseSeverity": "HIGH",
"attackVector": "NETWORK",
"attackComplexity": "LOW",
"attackRequirements": "NONE",
"privilegesRequired": "NONE",
"userInteraction": "NONE",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "NONE",
"vulnAvailabilityImpact": "HIGH",
"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-409"
}
]
}
],
"references": [
{
"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",
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
}
]
}