# CVE-2026-33257: Insufficient input validation of internal webserver

> Attackers can cause denial of service via unlimited memory allocation in the internal web server, which is disabled by default.

- **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-2026-33257, GHSA-p687-4q66-wh3p, UBUNTU-CVE-2026-33257

## What is CVE-2026-33257?

CVE-2026-33257 is a medium-severity denial of service vulnerability in Powerdns Recursor, 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 send a web request that causes unlimited memory allocation in the internal web server, leading to a denial of service. The internal web server is disabled by default.

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

## Which versions are affected by CVE-2026-33257?

It affects 3 products.


Products: Powerdns Authoritative, Powerdns Dnsdist, Powerdns Recursor.

## How do I fix CVE-2026-33257?

Apply the vendor's patch.

## Is CVE-2026-33257 being exploited?

There is no known exploitation of CVE-2026-33257 in the wild and no public exploit code.

## Other vulnerabilities in Powerdns Recursor

- [CVE-2020-24698](https://insights.sbomify.com/CVE-2020-24698/): Use after free in n/a (critical 9.8)
- [CVE-2020-24696](https://insights.sbomify.com/CVE-2020-24696/): Race condition in n/a (high 8.1)
- [CVE-2015-5470](https://insights.sbomify.com/CVE-2015-5470/): Denial of service in n/a (high 7.8)
- [CVE-2026-42001](https://insights.sbomify.com/CVE-2026-42001/): Insufficient Validation of Autoprimary SOA Queries (high 7.5)
- [CVE-2020-24697](https://insights.sbomify.com/CVE-2020-24697/): Denial of service in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-33257 and fix it if it is affected.

What it is: CVE-2026-33257 is a medium-severity denial of service vulnerability in Powerdns Recursor, 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-2026-33257 in the wild and no public exploit code.

Affected product: Powerdns Recursor. 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-2026-33257/ (Markdown: https://insights.sbomify.com/CVE-2026-33257/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33257
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33257
- OSV: https://osv.dev/vulnerability/CVE-2026-33257

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-33257/
Summaries are generated and may contain mistakes; the official description above is the record.