CVE-2025-11411: nlnet labs unbound

Vulnerability summary

CVE-2025-11411 is a medium (CVSS 5.7) vulnerability in nlnet labs unbound. EPSS estimates a 0.33% chance of exploitation in the next 30 days, higher than 24.7% of scored vulnerabilities.

Timeline

1. 22-10-2025
   PublishedVulnerability first disclosed.
2. 05-12-2025
   Last modifiedVulnerability information updated.

Description

NLnet Labs Unbound up to and including version 1.24.1 is vulnerable to possible domain hijack attacks. Promiscuous NS RRSets that complement positive DNS replies in the authority section can be used to trick resolvers to update their delegation information for the zone. Usually these RRSets are used to update the resolver's knowledge of the zone's name servers. A malicious actor can exploit the possible poisonous effect by injecting NS RRSets (and possibly their respective address records) in a reply. This could be done for example by trying to spoof a packet or fragmentation attacks. Unbound would then proceed to update the NS RRSet data it already has since the new data has enough trust for it, i.e., in-zone data for the delegation point. Unbound 1.24.1 includes a fix that scrubs unsolicited NS RRSets (and their respective address records) from replies mitigating the possible poison effect. Unbound 1.24.2 includes an additional fix that scrubs unsolicited NS RRSets (and their respective address records) from YXDOMAIN and non-referral nodata replies, further mitigating the possible poison effect.

• CWE-349Acceptance of Extraneous Untrusted Data With Trusted DataThe product, when processing trusted data, accepts any untrusted data that is also included with the trusted data, treating the untrusted data as if it were trusted.