CVE-2026-93471
HIGH 8.7Improper 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.
Severe if exploited (CVSS 8.7), but no known exploitation and low modeled probability. Patch on a normal cadence.
Exploitation likelihood
0.4%chance of exploitation in 30 days · 38th percentile
Impact if exploited
8.7CVSS 4.0 · HIGH
- ConfidentialityNone
- IntegrityNone
- AvailabilityHigh
What an attacker needs
- ✓Access: Reachable over the network — no local access needed
- ✓Privileges: No account or privileges required
- ✓User interaction: No user interaction needed
- ✓Complexity: No special conditions — reliably repeatable
- ✓Requirements: No special attack requirements
✓ lowers the bar for an attacker · ⚠ raises it
Proof of concept
No public PoC is currently catalogued.
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Data snapshot:
Weakness (CWE)
- CWE-409: Improper Handling of Highly Compressed Data (Data Amplification)
CVSS vector
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
References and research data (JSON)
All CVSS metrics
- HIGH 8.7 v4.0 · CNA Primary
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 - HIGH 8.7 v4.0 · NVD Secondary
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
References
Advisories
- https://cna.erlef.org/cves/CVE-2026-93471.html CVE record · EEF · Updated 2026-10-22T06:59:24.029Z
NVD · CVE-2026-93471 · Updated 2026-10-22T16:58:51.997 - https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-108052 EUVD · EUVD-2026-108052
Technical & other
- https://osv.dev/vulnerability/EEF-CVE-2026-93471 CVE record · EEF · Updated 2026-10-22T06:59:24.029Z
NVD · CVE-2026-93471 · Updated 2026-10-22T16:58:51.997 - https://github.com/handnot2/esaml/commit/deeb84378d5c82153b470e99d24f77c38afca14a CVE record · EEF · Updated 2026-10-22T06:59:24.029Z
NVD · CVE-2026-93471 · Updated 2026-10-22T16:58:51.997 - https://github.com/arekinath/esaml/commit/deeb84378d5c82153b470e99d24f77c38afca14a CVE record · EEF · Updated 2026-10-22T06:59:24.029Z
NVD · CVE-2026-93471 · Updated 2026-10-22T16:58:51.997 - https://github.com/dropbox/esaml/commit/deeb84378d5c82153b470e99d24f77c38afca14a CVE record · EEF · Updated 2026-10-22T06:59:24.029Z
NVD · CVE-2026-93471 · Updated 2026-10-22T16:58:51.997