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).
History

Wed, 20 May 2026 23:00:00 +0000

Type Values Removed Values Added
First Time appeared Nlnetlabs
Nlnetlabs unbound
CPEs cpe:2.3:a:nlnetlabs:unbound:*:*:*:*:*:*:*:*
Vendors & Products Nlnetlabs
Nlnetlabs unbound
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


Wed, 20 May 2026 13:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 20 May 2026 10:00:00 +0000

Type Values Removed Values Added
Description 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).
Title Long list of incoming EDNS options degrades performance
Weaknesses CWE-407
CWE-770
References
Metrics cvssV4_0

{'score': 6.6, 'vector': '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/U:Red'}


cve-icon MITRE

Status: PUBLISHED

Assigner: NLnet Labs

Published:

Updated: 2026-05-20T12:11:23.425Z

Reserved: 2026-05-07T10:13:43.992Z

Link: CVE-2026-41292

cve-icon Vulnrichment

Updated: 2026-05-20T12:11:18.415Z

cve-icon NVD

Status : Analyzed

Published: 2026-05-20T10:16:27.327

Modified: 2026-05-20T22:49:46.850

Link: CVE-2026-41292

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-20T11:30:26Z