PowerDNS Security Advisory 2026-03 for PowerDNS Recursor: Multiple issues¶
CVE-2026-33256: Unbounded memory allocation by internal web server¶
CVE: CVE-2026-33256
Date: 2026-04-22T00:00:00+01:00
Discovery date: 2026-02-17T00:00:00+01:00
Affects: PowerDNS Recursor from 5.3.0 up to and including 5.4.0
Not affected: PowerDNS Recursor 5.3.6, 5.4.1
Severity: Medium
Impact: Denial of service
Exploit: This problem can be triggered by an attacker sending crafted http requests, but only if the internal webserver is enabled.
Risk of system compromise: None
Solution: Upgrade to patched version or disallow network access to web server
CWE: CWE-770
CVSS: 3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Last affected: 5.3.5,5.4.0
First fixed: 5.3.6,5.4.1
Internal ID: 365
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.
The remedy is: upgrade to a patched version, or prevent network access to the internal webserver. In general for defense in-depth reasons we recommend making the internal web server only accessible to trusted clients.
We would like to thank Ap4sh - Samy Medjahed and Ethicxz - Eliott Laurie Ap4sh / Ethicxz for bringing this issue to our attention.
CVE-2026-33257: Insufficient input validation of internal web server¶
CVE: CVE-2026-33257
Date: 2026-04-22T00:00:00+01:00
Discovery date: 2026-02-16T00:00:00+01:00
Affects: PowerDNS Recursor up to and including 5.2.8
Not affected: PowerDNS Recursor 5.2.9
Severity: Medium
Impact: Denial of service
Exploit: This problem can be triggered by an attacker sending crafted http requests, but only if the internal webserver is enabled.
Risk of system compromise: None
Solution: Upgrade to patched version or disallow network access to web server
CWE: CWE-770
CVSS: 3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Last affected: 5.2.8
First fixed: 5.2.9
Internal ID: 368
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.
The remedy is: upgrade to a patched version, or prevent network access to the internal webserver. In general for defense in-depth reasons we recommend making the internal web server only accessible to trusted clients.
We would like to thank Vitaly Simonovich for bringing this issue to our attention.
CVE-2026-33258: Crafted zones can cause increased resource usage¶
CVE: CVE-2026-33258
Date: 2026-04-22T00:00:00+01:00
Discovery date: 2026-02-28T00:00:00+01:00
Affects: PowerDNS Recursor up to and including 5.2.8, 5.3.5, 5.4.0
Not affected: PowerDNS Recursor 5.2.9, 5.3.6, 5.4.1
Severity: Medium
Impact: Denial of service
Exploit: This problem can be triggered by an attacker sending crafted DNS responses
Risk of system compromise: None
Solution: Upgrade to patched version
CWE: CWE-770
CVSS: 3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Last affected: 5.2.8, 5.3.5, 5.4.0
First fixed: 5.2.9, 5.3.6, 5.4.1
Internal ID: 369
By publishing and querying a crafted zone an attacker can cause allocation of large entries in the negative and aggressive NSEC(3) caches.
The remedy is: upgrade to a patched version.
We would like to thank Haruto Kimura (Stella) for bringing this issue to our attention.
CVE-2026-33259: Concurrent modification of RPZ data can lead to denial of service¶
CVE: CVE-2026-33259
Date: 2026-04-22T00:00:00+01:00
Discovery date: 2026-02-28T00:00:00+01:00
Affects: PowerDNS Recursor up to and including 5.2.8, 5.3.5, 5.4.0
Not affected: PowerDNS Recursor 5.2.9, 5.3.6, 5.4.1
Severity: Medium
Impact: Denial of service
Exploit: This problem can be triggered by having many concurrent transfers of the same RPZ
Risk of system compromise: None
Solution: Upgrade to patched version
CWE: CWE-416
CVSS: 3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:H
Last affected: 5.2.8, 5.3.5, 5.4.0
First fixed: 5.2.9, 5.3.6, 5.4.1
Internal ID: 370
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.
The remedy is: upgrade to a patched version.
We would like to thank Haruto Kimura (Stella) for bringing this issue to our attention.
CVE-2026-33260: Insufficient input validation of internal web server¶
CVE: CVE-2026-33260
Date: 2026-04-22T00:00:00+01:00
Discovery date: 2026-02-20T00:00:00+01:00
Affects: PowerDNS Recursor up to and including 5.2.8
Not affected: PowerDNS Recursor 5.2.9
Severity: Medium
Impact: Denial of service
Exploit: This problem can be triggered by an attacker sending crafted http requests, but only if the internal webserver is enabled.
Risk of system compromise: None
Solution: Upgrade to patched version or disallow network access to web server
CWE: CWE-770
CVSS: 3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Last affected: 5.2.8
First fixed: 5.2.9
Internal ID: 374
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.
The remedy is: upgrade to a patched version, or prevent network access to the internal webserver. In general for defense in-depth reasons we recommend making the internal web server only accessible to trusted clients.
We would like to thank Cavid for bringing this issue to our attention.
CVE-2026-33261: Null pointer access in aggressive NSEC(3) cache¶
CVE: CVE-2026-33261
Date: 2026-04-22T00:00:00+01:00
Discovery date: 2026-03-13T00:00:00+01:00
Affects: PowerDNS Recursor up to and including 5.2.8, 5.3.5, 5.4.0
Not affected: PowerDNS Recursor 5.2.9, 5.3.6, 5.4.1
Severity: Medium
Impact: Denial of service
Exploit: This problem can be triggered by a zone transitioning from NSEC to NSEC3
Risk of system compromise: None
Solution: Upgrade to patched version
CWE: CWE-353
CVSS: 3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Last affected: 5.2.8, 5.3.5, 5.4.0
First fixed: 5.2.9, 5.3.6, 5.4.1
Internal ID: 382
A zone transition from NSEC to NSEC3 might trigger an internal inconsistency and cause a denial of service.
The remedy is: upgrade to a patched version.
We would like to thank ylwango613 for bringing this issue to our attention.
CVE-2026-33262: Insufficient validation of cookie reply¶
CVE: CVE-2026-33262
Date: 2026-04-22T00:00:00+01:00
Discovery date: 2026-03-12T00:00:00+01:00
Affects: PowerDNS Recursor 5.4.0
Not affected: PowerDNS Recursor 5.4.1
Severity: Medium
Impact: Denial of service
Exploit: This problem can be triggered by an attacker sending crafted DNS responses, but only if cookies are enabled
Risk of system compromise: None
Solution: Upgrade to patched version
CWE: CWE-476
CVSS: 3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Last affected: 5.4.0
First fixed: 5.4.1
Internal ID: 386
An attacker can send replies that result in a null pointer dereference, caused by a missing consistency check and leading to a denial of service. Cookies are disabled by default.
The remedy is: upgrade to a patched version.
We would like to thank ylwango613 for bringing this issue to our attention.
CVE-2026-33601: Insufficient validation of ZONEMD record¶
CVE: CVE-2026-33601
Date: 2026-04-22T00:00:00+01:00
Discovery date: 2026-03-25T00:00:00+01:00
Affects: PowerDNS Recursor up to and including 5.2.8, 5.3.5, 5.4.0
Not affected: PowerDNS Recursor 5.2.9, 5.3.6, 5.4.1
Severity: Medium
Impact: Denial of service
Exploit: This problem can be triggered by an attacker sending crafted zonemd record (only if zoneToCache is configured)
Risk of system compromise: None
Solution: Upgrade to patched version
CWE: CWE-476
CVSS: 3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H
Last affected: 5.2.8, 5.3.5, 5.4.0
First fixed: 5.2.9, 5.3.6, 5.4.1
Internal ID: 386
If you use the zoneToCache function with a malicious authoritative server, an attacker can send a zone that result in a null pointer dereference, caused by a missing consistency check and leading to a denial of service.
The remedy is: upgrade to a patched version.
We would like to thank ylwango613 for bringing this issue to our attention.
CVE-2026-33600: Null pointer dereference in RPZ transfer¶
CVE: CVE-2026-33600
Date: 2026-04-22T00:00:00+01:00
Discovery date: 2026-03-27T00:00:00+01:00
Affects: PowerDNS Recursor up to and including 5.2.8, 5.3.5, 5.4.0
Not affected: PowerDNS Recursor 5.2.9, 5.3.6, 5.4.1
Severity: Medium
Impact: Denial of service
Exploit: This problem can be triggered by an attacker sending a crafted RPZ
Risk of system compromise: None
Solution: Upgrade to patched version
CWE: CWE-476
CVSS: 3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H
Last affected: 5.2.8, 5.3.5, 5.4.0
First fixed: 5.2.9, 5.3.6, 5.4.1
Internal ID: 432
An RPZ sent by a malicious authoritative server can result in a null pointer dereference, caused by a missing consistency check and leading to a denial of service.
The remedy is: upgrade to a patched version.
We would like to thank ylwango613 for bringing this issue to our attention.