CVE-2026-40011 Prometheus denial of service via crafted DNS queries
Attackers can cause denial of service in Prometheus monitoring by sending crafted DNS queries to PowerDNS DNSdist, blocking valid scrapes.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-40011?
CVE-2026-40011 is a low-severity denial of service vulnerability in PowerDNS DNSdist, published on 25 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
An attacker sending a large number of crafted DNS queries might be able to trigger a dynamic block being inserted with a value causing invalid output to be produced in the prometheus endpoint. The prometheus endpoint will then be rejected by the scraper until the dynamic block expires.
Weakness: CWE-116
Which versions are affected by CVE-2026-40011?
How do I fix CVE-2026-40011?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-40011 being exploited?
There is no known exploitation of CVE-2026-40011 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-40011, GHSA-f83r-q8f4-f336, UBUNTU-CVE-2026-40011.