CVE-2025-30187 Denial of service via crafted DoH exchange in PowerDNS DNSdist
An attacker can cause a denial of service in PowerDNS DNSdist by triggering an unbounded I/O read loop during DNS over HTTPS processing.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-30187?
CVE-2025-30187 is a low-severity denial of service vulnerability in PowerDNS DNSdist, published on 18 Sep 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In some circumstances, when DNSdist is configured to use the nghttp2 library to process incoming DNS over HTTPS queries, an attacker might be able to cause a denial of service by crafting a DoH exchange that triggers an unbounded I/O read loop, causing an unexpected consumption of CPU resources.
Weakness: CWE-835
Which versions are affected by CVE-2025-30187?
How do I fix CVE-2025-30187?
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-2025-30187 being exploited?
There is no known exploitation of CVE-2025-30187 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2025-30187, GHSA-2qmc-ch65-q9cm, UBUNTU-CVE-2025-30187.