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CVE-2026-40211— Denial of service via crafted DoH3 queries

Quick assessment

Affected
PowerDNS DNSdist
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

PowerDNS dnsdist是PowerDNS公司开源的一款高性能DNS流量分发与防护工具。 PowerDNS DNSdist 1.9.0版本至1.9.15之前版本和2.0.0版本至2.0.7之前版本存在资源管理错误漏洞，该漏洞源于发送特制DNS over HTTP/3查询时触发异常，导致缓冲区无法立即释放，可能引发内存不足条件，造成拒绝服务。

CVSS 5.3 · Medium EPSS 0.30% · P22

Affected Version Matrix 2

VendorProduct Version RangeStatus
PowerDNS DNSdist 1.9.0< 1.9.15 affected
2.0.0< 2.0.7 affected
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I. Basic Information for CVE-2026-40211

Vulnerability Information
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Vulnerability Title
Denial of service via crafted DoH3 queries
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
PowerDNS DNSdist 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
PowerDNS dnsdist是PowerDNS公司开源的一款高性能DNS流量分发与防护工具。 PowerDNS DNSdist 1.9.0版本至1.9.15之前版本和2.0.0版本至2.0.7之前版本存在资源管理错误漏洞，该漏洞源于发送特制DNS over HTTP/3查询时触发异常，导致缓冲区无法立即释放，可能引发内存不足条件，造成拒绝服务。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
PowerDNS DNSdist 1.9.0 ~ 1.9.15 -

II. Public POCs for CVE-2026-40211

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III. Intelligence Information for CVE-2026-40211

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Vendor Advisories for CVE-2026-40211 (1)

Same Patch Batch · PowerDNS · 2026-06-25 · 14 CVEs total

CVE-2026-33612 7.5 HIGH ZoneToCache can poison the cache
CVE-2026-42387 5.9 MEDIUM Insufficient input validation in ZoneToCache
CVE-2026-42388 5.9 MEDIUM Missing input validation for catalog zones
CVE-2026-52690 5.9 MEDIUM Spoofed answers can mark an authoritative non-EDNS capable
CVE-2026-42390 5.3 MEDIUM ZONEMD validation can be bypassed
CVE-2026-42389 5.3 MEDIUM Reject more queries with invalid header values
CVE-2026-40209 5.3 MEDIUM Denial of service via IXFR queries
CVE-2026-40012 5.3 MEDIUM Information about ECS zero scoped answers might leak to clients that use a specific ECS
CVE-2026-40210 4.8 MEDIUM Out-of-bounds read in SetMacAddrAction
CVE-2026-42005 4.3 MEDIUM Insufficient input validation of internal web server
CVE-2026-42004 3.7 LOW EDNS options smuggling
CVE-2026-40011 3.7 LOW Prometheus denial of service via crafted DNS queries
CVE-2026-40208 3.7 LOW Denial of service via DoH3 queries

IV. Related Vulnerabilities

Same product: DNSdist
Same vendor: PowerDNS

V. Comments for CVE-2026-40211

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