CVE-2026-8466Network attack vector

Service interruption via unbounded multipart header buffering

Published May 13, 2026 · Updated May 13, 2026

Resource exhaustion in Nine Nines Cowboy 2.0.0 through 2.14.2 allows remote attackers to interrupt HTTP services via crafted multipart uploads. The cowboy_req:read_part/3 routine appends request bytes to its Buffer whenever multipart headers remain incomplete, without enforcing an upper bound. An exposed endpoint that calls read_part/1 or read_part/2 is required; a few concurrent uploads can exhaust BEAM memory and stop the service.

CVSS severity8.2
High
EPSS probability0.38%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Nine Nines Cowboy 2.0.0 through 2.14.2 allows remote attackers to interrupt HTTP services via crafted multipart uploads. The cowboy_req:read_part/3 routine appends request bytes to its Buffer whenever multipart headers remain incomplete, without enforcing an upper bound. An exposed endpoint that calls read_part/1 or read_part/2 is required; a few concurrent uploads can exhaust BEAM memory and stop the service.

The record

CVE
CVE-2026-8466
Published
May 13, 2026
Updated
May 13, 2026
Vendor
Nine Nines
Product
Cowboy
Classifications
CWE-770, CAPEC-130, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 13, 2026CVE publishedPublication date reported by the CVE source.
  2. May 13, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.0.0 <2.15.0
  2. Affected versionversion=917cf99e10c41676183d501b86af6e47c95afb89 <5c6a2061b41bb5771c4659fac7d5a822dca5bafb

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Nine Nines · Cowboyversion=2.0.0 <2.15.0; version=917cf99e10c41676183d501b86af6e47c95afb89 <5c6a2061b41bb5771c4659fac7d5a822dca5bafb

Published CVSS scores

8.2Erlang Ecosystem Foundation CNACVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
CAPEC-130Excessive Allocation
T1499.003Application Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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