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

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.

Published: 2026-04-22 Last update: 2026-04-27 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-33259 is rated Low Risk (20.1/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.01%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-33259

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-22 — 0.01% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-33259

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.0 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:H)
They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 0.7 4.2 [email protected]

Weakness enumeration for CVE-2026-33259

GitHub Security Advisory for CVE-2026-33259

GHSA-6c6h-9v3q-3wqm · Severity: medium — Having many concurrent transfers of the same RPZ can lead to inconsistent RPZ data, use after...

OS Trackers for CVE-2026-33259

vendor priority summary link
debian end-of-life CVE-2026-33259 end-of-life priority: Debian including 1 source packages (pdns-recursor), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 3, open 2. https://security-tracker.debian.org/tracker/CVE-2026-33259
ubuntu medium CVE-2026-33259 medium priority: Ubuntu including 1 source packages (pdns-recursor), 8 status rows across 8 suites (bionic, focal, jammy, noble, questing, resolute, upstream, xenial): needs-triage 7, released 1. https://ubuntu.com/security/CVE-2026-33259

Affected software / configurations for CVE-2026-33259

Vendor Product Version Raw CPE
powerdns recursor >= 5.2.0, < 5.2.9 cpe:2.3:a:powerdns:recursor:*:*:*:*:*:*:*:*
powerdns recursor >= 5.3.0, < 5.3.6 cpe:2.3:a:powerdns:recursor:*:*:*:*:*:*:*:*
powerdns recursor 5.4.0 cpe:2.3:a:powerdns:recursor:5.4.0:*:*:*:*:*:*:*

References for CVE-2026-33259

cvelogic Threat Intelligence