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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 denial of service vulnerability in the DNSSEC validator that can lead to a crash given malicious upstream replies. When Unbound constructs chase-reply messages for validation, the code uses the wrong counter to calculate write offsets for ADDITIONAL section rrsets. DNAME duplication could increase the ANSWER section count and authority filtering could decrease the AUTHORITY section count and create an uninitialized array slot. Combining these two, the validator later dereferences this uninitialized pointer, causing an immediate process crash. An adversary controlling a DNSSEC-signed domain can trigger this bug with a single query by configuring a DNAME chain with unsigned CNAMEs and a response containing unsigned AUTHORITY records alongside signed ADDITIONAL glue records. Unbound 1.25.1 contains a patch with a fix to use the proper counters to calculate the write offsets.
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Title: Unbound de NLnet Labs, Description: NLnet Labs Unbound hasta e incluyendo la versión 1.25.0 tiene una vulnerabilidad de denegación de servicio en el validador DNSSEC que puede llevar a un fallo dadas respuestas maliciosas de upstream. Cuando Unbound construye mensajes de respuesta de seguimiento para la validación, el código usa el contador incorrecto para calcular los offsets de escritura para los rrsets de la sección ADDITIONAL. La duplicación de DNAME podría aumentar el recuento de la sección ANSWER y el filtrado de autoridad podría disminuir el recuento de la sección AUTHORITY y crear una ranura de array no inicializada. Combinando estos dos, el validador luego desreferencia este puntero no inicializado, causando un fallo inmediato del proceso. Un adversario que controla un dominio firmado con DNSSEC puede activar este error con una sola consulta configurando una cadena DNAME con CNAMEs no firmados y una respuesta que contenga registros AUTHORITY no firmados junto con registros glue ADDITIONAL firmados. Unbound 1.25.1 contiene un parche con una solución para usar los contadores adecuados para calcular los offsets de escritura.
CVE Modified by redhat-SADP7/14/2026 10:21:39 PM
Action
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Affected
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[{"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:10.2"],"versions":[{"version":"0:1.24.2-7.el10_2.1","lessThan":"*","versionType":"rpm","status":"unaffected"}]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 8","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"unbound","cpes":["cpe:/a:redhat:enterprise_linux:8"],"versions":[{"version":"0:1.16.2-5.11.el8_10","lessThan":"*","versionType":"rpm","status":"unaffected"}]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 9","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"unbound","cpes":["cpe:/a:redhat:enterprise_linux:9"],"versions":[{"version":"0:1.24.2-3.el9_8.1","lessThan":"*","versionType":"rpm","status":"unaffected"}]},{"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":"1.25.1-0.1.hum1","lessThan":"*","versionType":"rpm","status":"unaffected"}]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 6","defaultStatus":"unknown","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 OpenShift Container Platform 4","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"rhcos","cpes":["cpe:/a:redhat:openshift
[{"vendor":"Red Hat","product":"Red Hat Enterprise Linux AppStream (v. 10)","defaultStatus":"affected","cpes":["cpe:/o:redhat:enterprise_linux:10.2"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux AppStream (v. 8)","defaultStatus":"affected","cpes":["cpe:/a:redhat:enterprise_linux:8::appstream"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux AppStream (v. 9)","defaultStatus":"affected","cpes":["cpe:/a:redhat:enterprise_linux:9::appstream"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)","defaultStatus":"affected","cpes":["cpe:/o:redhat:enterprise_linux:10.2"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)","defaultStatus":"affected","cpes":["cpe:/a:redhat:enterprise_linux:9::crb"]},{"vendor":"Red Hat","product":"Red Hat Hardened Images","defaultStatus":"affected","cpes":["cpe:/a:redhat:hummingbird:1"]},{"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 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 denial of service vulnerability in the DNSSEC validator that can lead to a crash given malicious upstream replies. When Unbound constructs chase-reply messages for validation, the code uses the wrong counter to calculate write offsets for ADDITIONAL section rrsets. DNAME duplication could increase the ANSWER section count and authority filtering could decrease the AUTHORITY section count and create an uninitialized array slot. Combining these two, the validator later dereferences this uninitialized pointer, causing an immediate process crash. An adversary controlling a DNSSEC-signed domain can trigger this bug with a single query by configuring a DNAME chain with unsigned CNAMEs and a response containing unsigned AUTHORITY records alongside signed ADDITIONAL glue records. Unbound 1.25.1 contains a patch with a fix to use the proper counters to calculate the write offsets.
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