CVE-2026-40211Network attack vector

Denial of service via retained DoH3 buffers

Published Jun 25, 2026 · Updated Jun 25, 2026

Resource exhaustion in PowerDNS DNSdist 1.9.0 through 1.9.14 and 2.0.0 through 2.0.6 allows remote attackers to interrupt service. An exception while processing a crafted DoH3 query retains its request buffer until the associated QUIC connection ends instead of releasing it immediately. Incoming DoH3 must be enabled, and enough concurrent streams must remain open to exhaust available memory and interrupt the DNS proxy.

CVSS severity5.3
Medium
EPSS probability0.30%
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 PowerDNS DNSdist 1.9.0 through 1.9.14 and 2.0.0 through 2.0.6 allows remote attackers to interrupt service. An exception while processing a crafted DoH3 query retains its request buffer until the associated QUIC connection ends instead of releasing it immediately. Incoming DoH3 must be enabled, and enough concurrent streams must remain open to exhaust available memory and interrupt the DNS proxy.

The record

CVE
CVE-2026-40211
Published
Jun 25, 2026
Updated
Jun 25, 2026
Vendor
PowerDNS
Product
DNSdist
Classifications
CWE-770, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 25, 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=1.9.0 <1.9.15
  2. Affected versionversion=2.0.0 <2.0.7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

PowerDNS · DNSdistversion=1.9.0 <1.9.15; version=2.0.0 <2.0.7

Published CVSS scores

5.3Open-XchangeCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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
T1499.004Application or System Exploitation

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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