CVE-2026-16756Network attack vector

Unauthenticated service interruption via incomplete HTTP requests

Published Jul 23, 2026 · Updated Jul 23, 2026

Slowloris denial of service in Amazon Web Services aws-smithy-http-server 0.66.4 and earlier allows remote attackers to interrupt services. The default serve() path sets no connection or header-read timeout and enforces no concurrent-connection cap, so partial requests retain sockets and tasks indefinitely. Unauthenticated network access is sufficient; many deliberately incomplete requests exhaust server resources and stop legitimate request handling.

CVSS severity8.7
High
EPSS probability0.75%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Slowloris denial of service in Amazon Web Services aws-smithy-http-server 0.66.4 and earlier allows remote attackers to interrupt services. The default serve() path sets no connection or header-read timeout and enforces no concurrent-connection cap, so partial requests retain sockets and tasks indefinitely. Unauthenticated network access is sufficient; many deliberately incomplete requests exhaust server resources and stop legitimate request handling.

The record

CVE
CVE-2026-16756
Published
Jul 23, 2026
Updated
Jul 23, 2026
Vendor
Amazon Web Services
Product
aws-smithy-http-server
Classifications
CWE-770, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 23, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 23, 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=0 <=0.66.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Amazon Web Services · aws-smithy-http-serverversion=0 <=0.66.4

Published CVSS scores

8.7Amazon Web ServicesCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
7.5Amazon Web ServicesCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 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
T1499.003Application Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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