CVE-2026-33256 Unbounded memory allocation by internal web server
An attacker can cause denial of service via unbounded memory allocation in the internal web server, which is disabled by default.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-33256?
CVE-2026-33256 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
Which versions are affected by CVE-2026-33256?
It affects 1 product.
Products include Powerdns Recursor.
How do I fix CVE-2026-33256?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-33256 being exploited?
There is no known exploitation of CVE-2026-33256 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-2026-33256, GHSA-f4c2-g8rq-pq9h, UBUNTU-CVE-2026-33256.