# CVE-2026-33254: Resource exhaustion via DoQ/DoH3 connections

> Attackers can cause denial of service via memory exhaustion in DNSdist when DoQ or DoH3 are enabled, requiring administrators to apply patches or disable features.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/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:** 22 Apr 2026
- **Updated:** 22 Apr 2026
- **Also known as:** DEBIAN-CVE-2026-33254, GHSA-wgv5-fpv8-m4jc, UBUNTU-CVE-2026-33254

## What is CVE-2026-33254?

CVE-2026-33254 is a medium-severity denial of service vulnerability in PowerDNS DNSdist, published on 22 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An attacker can create a large number of concurrent DoQ or DoH3 connections, causing unlimited memory allocation in DNSdist and leading to a denial of service. DOQ and DoH3 are disabled by default.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling)

## Which versions are affected by CVE-2026-33254?

It affects 1 product.


Products: Powerdns Dnsdist.

## How do I fix CVE-2026-33254?

Apply the vendor's patch.

## Is CVE-2026-33254 being exploited?

There is no known exploitation of CVE-2026-33254 in the wild and no public exploit code.

## Other vulnerabilities in PowerDNS DNSdist

- [CVE-2017-7557](https://insights.sbomify.com/CVE-2017-7557/): Cross-site request forgery in dnsdist (high 8.8)
- [CVE-2026-33593](https://insights.sbomify.com/CVE-2026-33593/): Denial of service via crafted DNSCrypt query (high 7.5)
- [CVE-2026-33602](https://insights.sbomify.com/CVE-2026-33602/): Off-by-one access when processing crafted UDP responses (medium 6.5)
- [CVE-2026-24029](https://insights.sbomify.com/CVE-2026-24029/): DNS over HTTPS ACL bypass (medium 6.5)
- [CVE-2026-27853](https://insights.sbomify.com/CVE-2026-27853/): Out-of-bounds write when rewriting large DNS packets (medium 5.9)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-33254 and fix it if it is affected.

What it is: CVE-2026-33254 is a medium-severity denial of service vulnerability in PowerDNS DNSdist, published on 22 Apr 2026. 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-2026-33254 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-2026-33254/ (Markdown: https://insights.sbomify.com/CVE-2026-33254/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33254
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33254
- OSV: https://osv.dev/vulnerability/CVE-2026-33254

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-33254/
Summaries are generated and may contain mistakes; the official description above is the record.