Medium severity · published Jun 25, 2026
CVE-2026-42389
Reject more queries with invalid header values
5.3
CVSS
0.3%
EPSS
No
On KEV
Description
This fix provides extra hardening for the 5.4.x branch by doing extra validation of incoming answers from authoritative servers.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 22% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
RE
Recursor · PowerDNS
5.4.0 before 5.4.3 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-42389
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-42389
docs.powerdns.com
https://docs.powerdns.com/recursor/security-advisories/powerdns-advisory-powerdns-2026-08.html
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