CVE-2026-42923 Detail
Undergoing Enrichment
This CVE record is currently being enriched by team members, this process results in the association of reference link tags, CVSS, CWE, and CPE applicability statement data DescriptionNLnet Labs Unbound up to and including version 1.25.0 has a vulnerability in the DNSSEC validator where the code path to consult the negative cache for DS records does not take into account the limit on NSEC3 hash calculations introduced in 1.19.1. This leads to degradation of service during the attack. An adversary that controls a DNSSEC signed zone can exploit this by signing NSEC3 records with acceptably high iterations for child delegations and querying a vulnerable Unbound. Unbound will keep performing the allowed hash calculations on the NSEC3 records and will not limit the work by the mitigation introduced in 1.19.1. As a side effect, a global lock for the negative cache will be held for the duration of the hashing, blocking other threads that need to consult the negative cache. Coordinated attacks could raise the vulnerability to denial of service. Unbound 1.25.1 contains a patch with a fix to bound the vulnerable code path with the existing limit for NSEC3 hash calculations. Metrics
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CVSS 4.0 Severity and Vector Strings:
CNA: NLnet Labs
CVSS-B 6.9 MEDIUM
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/U:Amber
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Weakness Enumeration
Quick InfoCVE Dictionary Entry:CVE-2026-42923 NVD Published Date: 05/20/2026 NVD Last Modified: 05/20/2026 Source: NLnet Labs |
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