What’s Vulnerable › Vulnerabilities
CVE-2026-40209: Denial of service via IXFR 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-772
Description
An attacker might be able to cause outgoing TCP connections to backend to be stuck until a timeout occurs instead of being released immediately, by sending IXFR queries. This could be used to cause a denial of service if there is a limit to the number of concurrent connections to this backend, or if the process runs out of file descriptors.
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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