# CVE-2026-93471: Unbounded SAML message decompression in esaml allows memory exhaustion

> CVE-2026-93471: Unbounded SAML message decompression in esaml allows memory exhaustion. CVSS 8.7 (CVSS 4.0).

Canonical: https://rewindex.com/cve/CVE-2026-93471
Last updated: 2026-10-22T16:58:51Z

- Published: 2026-10-22 06:59 UTC · Updated: 2026-10-22 16:58 UTC · Assigner: EEF
- CVSS: 8.7 (CVSS 4.0) · Severity: High
- EPSS: 0.44%, 38th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-409

## 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.

## Affected vendors and products

- arekinath: esaml
- dropbox: esaml
- handnot2: esaml

## Tracked companies

- [Dropbox](https://rewindex.com/company/dropbox.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-93471)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-93471)
- [https://cna.erlef.org/cves/CVE-2026-93471.html](https://cna.erlef.org/cves/CVE-2026-93471.html)
- [https://github.com/arekinath/esaml/commit/deeb84378d5c82153b470e99d24f77c38afca14a](https://github.com/arekinath/esaml/commit/deeb84378d5c82153b470e99d24f77c38afca14a)
- [https://github.com/dropbox/esaml/commit/deeb84378d5c82153b470e99d24f77c38afca14a](https://github.com/dropbox/esaml/commit/deeb84378d5c82153b470e99d24f77c38afca14a)
- [https://github.com/handnot2/esaml/commit/deeb84378d5c82153b470e99d24f77c38afca14a](https://github.com/handnot2/esaml/commit/deeb84378d5c82153b470e99d24f77c38afca14a)
- [https://osv.dev/vulnerability/EEF-CVE-2026-93471](https://osv.dev/vulnerability/EEF-CVE-2026-93471)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2026-93471 · Markdown: https://rewindex.com/cve/CVE-2026-93471.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-93471 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T03:10:05.875Z