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CVE-2026-42960

Nlnetlabs Unbound vulnerability

10.0 CRITICALEPSS 0.27%
  1. Published20 May 2026

Description

NLnet Labs Unbound up to and including version 1.25.0 is vulnerable to poisoning via promiscuous records for the authority section. Promiscuous RRSets that complement DNS replies in the authority section can be used to trick Unbound to cache such records. If an adversary is able to attach such records in a reply (i.e., spoofed packet, fragmentation attack) he would be able to poison Unbound's cache. A malicious actor can exploit the possible poisonous effect by injecting RRSets other than NS that are also accompanied by address records in a reply, for example MX. This could be achieved by trying to spoof a reply packet or fragmentation attacks. Unbound would then accept the relative address records in the additional section and cache them if the authority RRSet has enough trust at this point, i.e., in-zone data for the delegation point. Unbound 1.25.1 contains a patch with a fix that disregards address records from the additional section if they are not explicitly relevant only to authority NS records, mitigating the possible poison effect. This is a complement fix to CVE-2025-11411.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeChanged
ConfidentialityNone
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:H

Affected products

Nlnetlabs Unbound< 1.25.1

Remediation

Fixed in
Nlnetlabs Unbound≥ 1.25.1

References

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Frequently asked

Is CVE-2026-42960 being actively exploited?

CVE-2026-42960 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.27%.

How severe is CVE-2026-42960?

CVE-2026-42960 has a CVSS 3.1 base score of 10.0, rated critical. EPSS estimates a 0.27% probability of exploitation.

Which products are affected by CVE-2026-42960?

Affected products include Nlnetlabs Unbound.

How do I fix CVE-2026-42960?

Upgrade affected software to a fixed version, for example Nlnetlabs Unbound 1.25.1 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.