high · 8.7 No patch yet

Unbounded SAML message decompression in esaml allows memory exhaustion

CVE-2026-93471 · EEF-CVE-2026-93471 · published 22 Oct 2026

How serious is it

  • Severity: high, CVSS score 8.7 out of 10.
  • No exploit prediction (EPSS) score yet.
  • Not on the CISA list of exploited vulnerabilities.
  • No public exploit in Exploit-DB.

Is your app affected by CVE-2026-93471?

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Who is affected

  • esaml (Hex) >= 0.1.0

How to check

  1. Look for esaml in your lockfile and compare its version with the range above.
  2. Or paste your lockfile into the checker: it lists every package with a known vulnerability, this one included.

How to fix

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  1. No fixed version of esaml yet. Replace or remove it, or apply the workaround in the advisory below.
  2. If a vulnerable version was live, check your logs and rotate the secrets that server could read.

The advisory

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.

Check your whole app

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References

Merged from OSV, CVE List. Last updated 1 Nov 2026. All vulnerabilities · RSS · JSON

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