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NLnet Labs Unbound EUVD-2026-31078

| CVE-2026-41292 MEDIUM
Inefficient Algorithmic Complexity (CWE-407)
2026-05-20 sep@nlnetlabs.nl GHSA-2wvj-gvc7-gfhx
6.6
CVSS 4.0
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CVSS VectorNVD

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Red
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
X

Lifecycle Timeline

2
Patch available
May 20, 2026 - 11:02 EUVD
Analysis Generated
May 20, 2026 - 10:33 vuln.today

DescriptionNVD

NLnet Labs Unbound up to and including version 1.25.0 is vulnerable to a degradation of service attack related to parsing long lists of incoming EDNS options. An adversary sending queries with too many EDNS options can hold Unbound threads hostage while they are parsing and creating internal data structures for the options. Coordinated attacks can result in degradation and/or denial of service. Unbound 1.25.1 contains a patch with a fix to limit acceptable incoming EDNS options (100).

AnalysisAI

Unbound DNS resolver versions up to and including 1.25.0 allow remote unauthenticated attackers to degrade or deny service by sending DNS queries carrying abnormally large numbers of EDNS options, causing resolver threads to become occupied with unbounded parsing and internal data structure allocation. Coordinated multi-source attacks amplify thread exhaustion into full denial of service for legitimate DNS clients. …

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Vendor StatusVendor

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EUVD-2026-31078 vulnerability details – vuln.today

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