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This CVE record has been updated after NVD enrichment efforts were completed. Enrichment data supplied by the NVD may require amendment due to these changes.
Description
NLnet Labs Unbound up to and including version 1.25.0 has a vulnerability in the jostle logic that could defeat its purpose and degrade resolution performance. Retransmits of the same query could renew the age of slow running queries and not allow the jostle logic to see them as aged and potential targets for replacement with new queries. An adversary who can query a vulnerable Unbound and who can control a domain name server that replies slowly and/or maliciously to Unbound's queries can exploit the vulnerability and degrade the resolution performance of Unbound. When Unbound's 'num-queries-per-thread' reaches its limit, the jostle logic kicks in. When a new query comes in, half of the available queries that are also slow to resolve are candidates for replacement. The vulnerability then happens because duplicate queries that need resolution would skew the aging result by using the timestamp of the latest duplicate query instead of the original one that started the resolution effort. Cache and local data response performance remains unaffected. Coordinated attacks could raise this to a denial of resolution service. Unbound 1.25.1 contains a patch with a fix to attach an initial, non-updatable start time for incoming queries that allow the jostle logic to work as intended.
Metrics
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[{"vendor":"Red Hat","product":"Red Hat Hardened Images","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"unbound-main","cpes":["cpe:/a:redhat:hummingbird:1"],"versions":[{"version":"1.25.1-2.hum1","lessThan":"*","versionType":"rpm","status":"unaffected"}]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 10","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"unbound","cpes":["cpe:/o:redhat:enterprise_linux:10"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 6","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"unbound","cpes":["cpe:/o:redhat:enterprise_linux:6"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 7","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"unbound","cpes":["cpe:/o:redhat:enterprise_linux:7"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 8","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"unbound","cpes":["cpe:/o:redhat:enterprise_linux:8"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 9","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"unbound","cpes":["cpe:/o:redhat:enterprise_linux:9"]},{"vendor":"Red Hat","product":"Red Hat OpenShift Container Platform 4","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"rhcos","cpes":["cpe:/a:redhat:openshift:4"]}]
CVE Modified by redhat-SADP7/14/2026 10:21:33 PM
Action
Type
Old Value
New Value
Changed
Affected
[{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 10","defaultStatus":"affected","cpes":["cpe:/o:redhat:enterprise_linux:10"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 6","defaultStatus":"affected","cpes":["cpe:/o:redhat:enterprise_linux:6"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 7","defaultStatus":"affected","cpes":["cpe:/o:redhat:enterprise_linux:7"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 8","defaultStatus":"affected","cpes":["cpe:/o:redhat:enterprise_linux:8"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 9","defaultStatus":"affected","cpes":["cpe:/o:redhat:enterprise_linux:9"]},{"vendor":"Red Hat","product":"Red Hat Hardened Images","defaultStatus":"affected","cpes":["cpe:/a:redhat:hummingbird:1"]},{"vendor":"Red Hat","product":"Red Hat OpenShift Container Platform 4","defaultStatus":"affected","cpes":["cpe:/a:redhat:openshift:4"]}]
[{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 10","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"unbound","cpes":["cpe:/o:redhat:enterprise_linux:10"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 6","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"unbound","cpes":["cpe:/o:redhat:enterprise_linux:6"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 7","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"unbound","cpes":["cpe:/o:redhat:enterprise_linux:7"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 8","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"unbound","cpes":["cpe:/o:redhat:enterprise_linux:8"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 9","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"unbound","cpes":["cpe:/o:redhat:enterprise_linux:9"]},{"vendor":"Red Hat","product":"Red Hat Hardened Images","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"unbound","cpes":["cpe:/a:redhat:hummingbird:1"]},{"vendor":"Red Hat","product":"Red Hat OpenShift Container Platform 4","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"rhcos","cpes":["cpe:/a:redhat:openshift:4"]}]
[{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 10","defaultStatus":"affected","cpes":["cpe:/o:redhat:enterprise_linux:10"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 6","defaultStatus":"affected","cpes":["cpe:/o:redhat:enterprise_linux:6"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 7","defaultStatus":"affected","cpes":["cpe:/o:redhat:enterprise_linux:7"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 8","defaultStatus":"affected","cpes":["cpe:/o:redhat:enterprise_linux:8"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 9","defaultStatus":"affected","cpes":["cpe:/o:redhat:enterprise_linux:9"]},{"vendor":"Red Hat","product":"Red Hat Hardened Images","defaultStatus":"affected","cpes":["cpe:/a:redhat:hummingbird:1"]},{"vendor":"Red Hat","product":"Red Hat OpenShift Container Platform 4","defaultStatus":"affected","cpes":["cpe:/a:redhat:openshift:4"]}]
New CVE Received from NLnet Labs5/20/2026 6:16:27 AM
Action
Type
Old Value
New Value
Added
Description
NLnet Labs Unbound up to and including version 1.25.0 has a vulnerability in the jostle logic that could defeat its purpose and degrade resolution performance. Retransmits of the same query could renew the age of slow running queries and not allow the jostle logic to see them as aged and potential targets for replacement with new queries. An adversary who can query a vulnerable Unbound and who can control a domain name server that replies slowly and/or maliciously to Unbound's queries can exploit the vulnerability and degrade the resolution performance of Unbound. When Unbound's 'num-queries-per-thread' reaches its limit, the jostle logic kicks in. When a new query comes in, half of the available queries that are also slow to resolve are candidates for replacement. The vulnerability then happens because duplicate queries that need resolution would skew the aging result by using the timestamp of the latest duplicate query instead of the original one that started the resolution effort. Cache and local data response performance remains unaffected. Coordinated attacks could raise this to a denial of resolution service. Unbound 1.25.1 contains a patch with a fix to attach an initial, non-updatable start time for incoming queries that allow the jostle logic to work as intended.
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