What’s Vulnerable › Vulnerabilities
CVE-2026-40211: Denial of service via crafted DoH3 queries
- Severity: medium (CVSS 5.3 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.7% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-06-25 · updated 2026-10-25
- Weakness: CWE-770
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.
Affected products
- PowerDNS DNSdist: from 1.9.0 before 1.9.15; from 2.0.0 before 2.0.7 — fixed in 1.9.15, 2.0.7
How to fix
Upgrade to a fixed version: PowerDNS DNSdist 1.9.15, 2.0.7. Check the vendor advisory for mitigations.
References
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