CVE-2026-40211: Allocation of Resources Without Limits or Throttling in PowerDNS DNSdist
An attacker can send crafted DNS over HTTP/3 queries, triggering an exception that prevents some buffer from being freed right away. The buffer will be freed at the end of the QUIC connection, but on some setups it might be possible to open enough concurrent DoH3 streams to trigger an out-of-memory condition, resulting in a denial of service.
AI Analysis
Technical Summary
This vulnerability in PowerDNS DNSdist involves allocation of resources without limits or throttling when handling DNS over HTTP/3 queries. An attacker can send specially crafted queries that trigger an exception preventing immediate buffer release. Although buffers are eventually freed at the end of the QUIC connection, on some setups, opening many concurrent DoH3 streams can exhaust memory, causing a denial of service. The affected versions are 1.9.0, 2.0.0, and all versions from 1.9.0 up to but not including 1.9.15, and from 2.0.0 up to but not including 2.0.7. There is no known exploit in the wild and no official remediation level or patch link has been provided.
Potential Impact
The vulnerability can cause denial of service by exhausting memory resources through concurrent DNS over HTTP/3 streams. It does not impact confidentiality or integrity, only availability. No known active exploitation has been reported.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, consider limiting the number of concurrent DoH3 streams or applying resource usage controls if possible. Monitor vendor communications for updates on official patches or mitigations.
CVE-2026-40211: Allocation of Resources Without Limits or Throttling in PowerDNS DNSdist
Description
An attacker can send crafted DNS over HTTP/3 queries, triggering an exception that prevents some buffer from being freed right away. The buffer will be freed at the end of the QUIC connection, but on some setups it might be possible to open enough concurrent DoH3 streams to trigger an out-of-memory condition, resulting in a denial of service.
CVSS v3.1
Score 5.3medium
Affected software
pkg:github/dnsdistRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability in PowerDNS DNSdist involves allocation of resources without limits or throttling when handling DNS over HTTP/3 queries. An attacker can send specially crafted queries that trigger an exception preventing immediate buffer release. Although buffers are eventually freed at the end of the QUIC connection, on some setups, opening many concurrent DoH3 streams can exhaust memory, causing a denial of service. The affected versions are 1.9.0, 2.0.0, and all versions from 1.9.0 up to but not including 1.9.15, and from 2.0.0 up to but not including 2.0.7. There is no known exploit in the wild and no official remediation level or patch link has been provided.
Potential Impact
The vulnerability can cause denial of service by exhausting memory resources through concurrent DNS over HTTP/3 streams. It does not impact confidentiality or integrity, only availability. No known active exploitation has been reported.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, consider limiting the number of concurrent DoH3 streams or applying resource usage controls if possible. Monitor vendor communications for updates on official patches or mitigations.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- OX
- Date Reserved
- 2026-04-10T07:11:39.060Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a3d2a1b4853345fc1f848fc
Added to database: 06/25/2026, 13:16:11 UTC
Last enriched: 06/25/2026, 13:31:10 UTC
Last updated: 08/09/2026, 00:41:14 UTC
Views: 105
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