CVE-2026-33261 Null pointer accces in aggressive NSEC(3) cache
Medium 5.9
Published
Updated
Check this codebase for CVE-2026-33261 and fix it if it is affected.
What it is: CVE-2026-33261 is a medium-severity 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-2026-33261 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-2026-33261/ (Markdown: https://insights.sbomify.com/CVE-2026-33261/index.md)
A null pointer dereference in PowerDNS Recursor during NSEC to NSEC3 zone transitions allows attackers to cause a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-33261?
CVE-2026-33261 is a medium-severity 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
A zone transition from NSEC to NSEC3 might trigger an internal inconsistency and cause a denial of service.
Weakness: CWE-353
Which versions are affected by CVE-2026-33261?
It affects 1 product.
Products include Powerdns Recursor.
How do I fix CVE-2026-33261?
Apply the vendor's patch.
Is CVE-2026-33261 being exploited?
There is no known exploitation of CVE-2026-33261 in the wild and no public exploit code.
Other vulnerabilities in Powerdns Recursor
- CVE-2009-4009 Memory corruption in n/a
- CVE-2020-10030 Memory corruption in n/a
- CVE-2025-59023 Crafted delegations or IP fragments can poison cached delegations in Recursor
- CVE-2025-59030 Insufficient validation of incoming notifies over TCP can lead to a denial of service in Recursor
- CVE-2023-22617 Denial of service in n/a
Sources
Also known as DEBIAN-CVE-2026-33261, GHSA-rq6v-8q98-rrj8, UBUNTU-CVE-2026-33261.