CVE-2026-33259: Concurrent modification of RPZ data can lead to denial of servce

Published Apr 22, 2026
·
Updated

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.

Affected Software

3 affected components
PowerDNS recursor>=5.2.0<5.2.9
PowerDNS recursor>=5.3.0<5.3.6
PowerDNS recursor=5.4.0

Event History

Apr 22, 2026
CVE Published
via MITRE·09:38 AM
Data Sourced
via MITRE·09:38 AM
DescriptionSeverityWeakness
Data Sourced
via NVD·10:16 AM
DescriptionSeverityWeaknessAffected Software
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Frequently Asked Questions

1

What is the severity of CVE-2026-33259?

The severity of CVE-2026-33259 is rated as medium with a score of 5.

2

What impact does CVE-2026-33259 have on PowerDNS recursor?

CVE-2026-33259 can lead to denial of service due to inconsistent RPZ data and potentially a crash of the recursor.

3

How do I fix CVE-2026-33259?

To mitigate CVE-2026-33259, ensure that concurrent transfers of the same RPZ zone are properly managed and avoid malfunctioning RPZ providers.

4

What conditions exacerbate CVE-2026-33259?

CVE-2026-33259 is exacerbated by having many concurrent transfers of the same RPZ zone, particularly with a malfunctioning RPZ provider.

5

What does 'use after free' mean in the context of CVE-2026-33259?

In the context of CVE-2026-33259, 'use after free' refers to accessing memory that has already been freed, which can occur when inconsistent RPZ data is processed.

Contact

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