CVE-2026-42960
Published:May 20, 2026
Updated:June 04, 2026
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.
Affected Packages
https://github.com/NLnetLabs/unbound.git (GITHUB):
Affected version(s) >=release-0.0 <release-1.25.1Fix Suggestion:
Update to version release-1.25.1Related Resources (1)
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Contact UsCVSS v4
Base Score:
5.7
Attack Vector
ADJACENT
Attack Complexity
LOW
Attack Requirements
PRESENT
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
HIGH
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
HIGH
Subsequent System Availability
HIGH
Exploit Maturity
POC
CVSS v3
Base Score:
7.4
Attack Vector
ADJACENT
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
NONE
Weakness Type (CWE)
Acceptance of Extraneous Untrusted Data With Trusted Data
EPSS
Base Score:
0.03