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NVD / CVE Program· CNA OX

CVE-2026-42389: Reject more queries with invalid header values

Noroxi assessment

Priority: Monitor (action score 21/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.29% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: PowerDNS Recursor 5.4.3.

Low priority for now. Upgrade to PowerDNS Recursor 5.4.3 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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

MediumCVSS 5.3 · v3.1—No exploit Fix available
Published
Jun 25, 2026
Updated
Oct 25, 2026
EPSS
0.2% · 22th percentile

Report tools

JSON

Action score

21

Monitor

Low priority for now.

CVSS
21 / 40 · 5.3 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · OX
5.3
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-42389

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (OX). Independent of NVD's CPE analysis and usually ahead of it.

  • PowerDNS Recursor

    • 5.4.0 and later · before 5.4.3affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:14pdns-recursorbefore 5.4.3-15.4.3-1

Same product

powerdns: all records

Other highest-scoring records for the same primary product.

  • CVE-2018-16855An issue has been found in PowerDNS Recursor before version 4.1.8 where a remote attacker sending a DNS query can trigger an out-of-bounds m
    48Plan
  • CVE-2017-15120An issue has been found in the parsing of authoritative answers in PowerDNS Recursor before 4.0.8, leading to a NULL pointer dereference whe
    45Plan
  • CVE-2009-4009Buffer overflow in PowerDNS Recursor before 3.1.7.2 allows remote attackers to cause a denial of service (daemon crash) or possibly execute
    45Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-42387Jun 25, 2026 · Insufficient input validation in ZoneToCache
    23Monitor
  • ← EarlierCVE-2026-42388Jun 25, 2026 · Missing input validation for catalog zones
    23Monitor
  • Later →CVE-2026-42390Jun 25, 2026 · ZONEMD validation can be bypassed
    21Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
PowerDNS Recursor5.4.3Vendor (CNA)
debian:pdns-recursor5.4.3-1 · Debian:14Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-423870 days apartInsufficient input validation in ZoneToCache
    23Monitor
  • CVE-2026-423880 days apartMissing input validation for catalog zones
    23Monitor
  • CVE-2026-423900 days apartZONEMD validation can be bypassed
    21Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
low · data or configuration can be modified
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
Low
Availability impact
None

Weakness class (CWE)

CWE-20 · Improper Input Validation

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records