# CVE-2026-33596: TCP backend stream ID overflow

> An attacker can cause query-response mismatches or service disruption in PowerDNS DNSdist by exploiting a stream ID overflow via timed queries.

- **Severity:** Low 3.1 (`CVSS:3.1/AV:A/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:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 22 Apr 2026
- **Updated:** 22 Apr 2026
- **Also known as:** DEBIAN-CVE-2026-33596, GHSA-jcpx-7c75-g6c9, UBUNTU-CVE-2026-33596

## What is CVE-2026-33596?

CVE-2026-33596 is a low-severity vulnerability in PowerDNS DNSdist, published on 22 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A client might theoretically be able to cause a mismatch between queries sent to a backend and the received responses by sending a flood of perfectly timed queries that are routed to a TCP-only or DNS over TLS backend.

Weakness: CWE-190 (Integer Overflow or Wraparound)

## Which versions are affected by CVE-2026-33596?

It affects 1 product.


Products: Powerdns Dnsdist.

## How do I fix CVE-2026-33596?

Apply the vendor's patch.

## Is CVE-2026-33596 being exploited?

There is no known exploitation of CVE-2026-33596 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-2026-33596 and fix it if it is affected.

What it is: CVE-2026-33596 is a low-severity vulnerability in PowerDNS DNSdist, published on 22 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-33596 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-2026-33596/ (Markdown: https://insights.sbomify.com/CVE-2026-33596/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33596
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33596
- OSV: https://osv.dev/vulnerability/CVE-2026-33596

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-33596/
Summaries are generated and may contain mistakes; the official description above is the record.