Reject more queries with invalid header values

published 2026-06-25 4 mo ago modified 2026-10-25 14 d ago also EUVD-2026-39388

cvss: 5.3; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 22%
public exploits: 0; none known

This fix provides extra hardening for the 5.4.x branch by doing extra validation of incoming answers from authoritative servers.

Patch / fix

fixed in 1 distros 1

PowerDNS Recursor 5.4.3

pdns-recursor Debian 14 5.4.3-1

debian advisories DEBIAN-CVE-2026-42389

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-42389 updated 2026-06-26 cvss 5.3

pdns-recursor: reject more queries with invalid header values

Red Hat All currently supported Red Hat products
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation: none
Automatable: yes
Technical impact: partial
Assessed: 4 mo ago (2026-06-25)

Exploit prediction

0.30% chance of exploitation in the next 30 days, higher than 22% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	5.3	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected products

PowerDNS Recursor

Classification

Weakness

CWE-20 Improper Input Validation

References

docs.powerdns.com /recursor/security-advisories/powerdns-advisory-powerdns-2026-08.html

Sources

CVE List CVE-2026-42389
NVD CVE-2026-42389

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary