# 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.

- **Severity:** Low 3.7 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Sep 2025
- **Updated:** 4 Nov 2025
- **Also known as:** DEBIAN-CVE-2025-30187, GHSA-2qmc-ch65-q9cm, UBUNTU-CVE-2025-30187

## 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 (Loop with Unreachable Exit Condition)

## Which versions are affected by CVE-2025-30187?


## How do I fix CVE-2025-30187?

Upgrade to a fixed version.

## Is CVE-2025-30187 being exploited?

There is no known exploitation of CVE-2025-30187 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-30187 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2025-30187 in the wild and no public exploit code.

Affected product: PowerDNS DNSdist. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-30187/ (Markdown: https://insights.sbomify.com/CVE-2025-30187/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-30187
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-30187
- OSV: https://osv.dev/vulnerability/CVE-2025-30187

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-30187/
Summaries are generated and may contain mistakes; the official description above is the record.