How severe is CVE-2026-42387?

CVE-2026-42387 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-42387 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (32nd percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-42387?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-42387 have an EU (EUVD) identifier?

Yes. CVE-2026-42387 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-39357.

When was CVE-2026-42387 published?

CVE-2026-42387 was published on 2026-06-25.

CVE-2026-42387

CVE-2026-42387 is a medium-severity vulnerability with a CVSS 3.x base score of 5.9. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-20.

Key facts

Severity: Medium (CVSS 3.x base score 5.9)
EPSS exploit prediction: 0% (32nd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-39357
Weakness: CWE-20
Published: 2026-06-25
Last modified: 2026-06-25

Description

A malicious authoritative server can send a crafted zone via the ZoneToCache function that leads to a crash of the Recursor due to insuffcient input validation.

Frequently asked questions

What is CVE-2026-42387?: A malicious authoritative server can send a crafted zone via the ZoneToCache function that leads to a crash of the Recursor due to insuffcient input validation.
How severe is CVE-2026-42387?: CVE-2026-42387 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-42387 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (32nd percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-42387?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-42387 have an EU (EUVD) identifier?: Yes. CVE-2026-42387 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-39357.
When was CVE-2026-42387 published?: CVE-2026-42387 was published on 2026-06-25.

References

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

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