CVE-2026-93471

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.

CVSS

No CVSS.

References

Link	Resource
https://cna.erlef.org/cves/CVE-2026-93471.html
https://github.com/arekinath/esaml/commit/deeb84378d5c82153b470e99d24f77c38afca14a
https://github.com/dropbox/esaml/commit/deeb84378d5c82153b470e99d24f77c38afca14a
https://github.com/handnot2/esaml/commit/deeb84378d5c82153b470e99d24f77c38afca14a
https://osv.dev/vulnerability/EEF-CVE-2026-93471
https://cna.erlef.org/cves/CVE-2026-93471.html
https://osv.dev/vulnerability/EEF-CVE-2026-93471

Configurations

No configuration.

History

30 Oct 2026, 19:20

Type	Values Removed	Values Added
References	~~() https://cna.erlef.org/cves/CVE-2026-93471.html -~~	() https://cna.erlef.org/cves/CVE-2026-93471.html -
References	~~() https://osv.dev/vulnerability/EEF-CVE-2026-93471 -~~	() https://osv.dev/vulnerability/EEF-CVE-2026-93471 -

22 Oct 2026, 09:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-10-22 09:17

Updated : 2026-10-30 19:20

NVD link : CVE-2026-93471

Mitre link : CVE-2026-93471

CVE.ORG link : CVE-2026-93471

JSON object : View

Products Affected

No product.

CWE

CWE-409

Improper Handling of Highly Compressed Data (Data Amplification)

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[{"cpes": ["cpe:2.3:a:handnot2:esaml:*:*:*:*:*:*:*:*"], "repo": "https://github.com/handnot2/esaml", "vendor": "handnot2", "modules": ["esaml_binding", "esaml_cowboy"], "product": "esaml", "versions": [{"status": "affected", "version": "deeb84378d5c82153b470e99d24f77c38afca14a", "lessThan": "*", "versionType": "git"}], "packageURL": "pkg:github/handnot2/esaml", "packageName": "handnot2/esaml", "programFiles": ["src/esaml_binding.erl", "src/esaml_cowboy.erl"], "collectionURL": "https://github.com", "defaultStatus": "unaffected", "programRoutines": [{"name": "esaml_binding:decode_response/2"}, {"name": "esaml_cowboy:validate_assertion/2"}, {"name": "esaml_cowboy:validate_logout/2"}]}, {"cpes": ["cpe:2.3:a:arekinath:esaml:*:*:*:*:*:*:*:*"], "repo": "https://github.com/arekinath/esaml", "vendor": "arekinath", "modules": ["esaml_binding", "esaml_cowboy"], "product": "esaml", "versions": [{"status": "affected", "version": "deeb84378d5c82153b470e99d24f77c38afca14a", "lessThan": "*", 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"esaml_cowboy:validate_logout/2"}]}, {"cpes": ["cpe:2.3:a:dropbox:esaml:*:*:*:*:*:*:*:*"], "repo": "https://github.com/dropbox/esaml", "vendor": "dropbox", "modules": ["esaml_binding", "esaml_cowboy"], "product": "esaml", "versions": [{"status": "affected", "version": "deeb84378d5c82153b470e99d24f77c38afca14a", "lessThan": "*", "versionType": "git"}], "packageURL": "pkg:github/dropbox/esaml", "packageName": "dropbox/esaml", "programFiles": ["src/esaml_binding.erl", "src/esaml_cowboy.erl"], "collectionURL": "https://github.com", "defaultStatus": "unaffected", "programRoutines": [{"name": "esaml_binding:decode_response/2"}, {"name": "esaml_cowboy:validate_assertion/2"}, {"name": "esaml_cowboy:validate_logout/2"}]}]}], "published": "2026-10-22T09:17:16.827", "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": 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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."}], "lastModified": "2026-10-30T19:20:19.010", "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}