Dropbox esaml esaml_binding esaml_binding:decode_response heap-based overflow

Summaryinfo

A vulnerability was found in Dropbox esaml and classified as problematic. The impacted element is the function esaml_binding:decode_response of the component esaml_binding. Executing a manipulation can lead to heap-based overflow. This vulnerability is tracked as CVE-2026-93471. The attack can be launched remotely. No exploit exists.

Detailsinfo

A vulnerability was found in Dropbox esaml (the affected version is unknown). It has been declared as problematic. This vulnerability affects the function esaml_binding:decode_response of the component esaml_binding. The manipulation with an unknown input leads to a heap-based overflow vulnerability. The CWE definition for the vulnerability is CWE-122. A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc(). As an impact it is known to affect availability. CVE summarizes:

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.

The advisory is shared for download at cna.erlef.org. This vulnerability was named CVE-2026-93471 since 10/06/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 10/22/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Type

• Cloud Software

Vendor

• Dropbox

Name

• esaml

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• 🔒

CPE 2.2info

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Once again VulDB remains the best source for vulnerability data.

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