CVE-2026-33259 Concurrent modification of RPZ data can lead to denial of servce
Concurrent RPZ transfers can cause use-after-free and crashes in PowerDNS Recursor, leading to denial of service.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-33259?
CVE-2026-33259 is a medium-severity use after free vulnerability in Powerdns Recursor, published on 22 Apr 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Official description
Having many concurrent transfers of the same RPZ can lead to inconsistent RPZ data, use after free and/or a crash of the recursor. Normally concurrent transfers of the same RPZ zone can only occur with a malfunctioning RPZ provider.
Weakness: CWE-416
Which versions are affected by CVE-2026-33259?
It affects 1 product.
Products include Powerdns Recursor.
How do I fix CVE-2026-33259?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-33259 being exploited?
There is no known exploitation of CVE-2026-33259 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-2026-33259, GHSA-6c6h-9v3q-3wqm, UBUNTU-CVE-2026-33259.