A multi-vendor cache poisoning vulnerability named 'Rebirthday Attack' has been discovered in caching resolvers that support EDNS Client Subnet (ECS). Unbound is also vulnerable when compiled with ECS support, i.e., '--enable-subnet', AND configured to send ECS information along with queries to upstream name servers, i.e., at least one of the 'send-client-subnet', 'client-subnet-zone' or 'client-subnet-always-forward' options is used. Resolvers supporting ECS need to segregate outgoing queries to accommodate for different outgoing ECS information. This re-opens up resolvers to a birthday paradox attack (Rebirthday Attack) that tries to match the DNS transaction ID in order to cache non-ECS poisonous replies.
This issue has been addressed in the following products: Red Hat Enterprise Linux 9 Via RHSA-2025:11849 https://access.redhat.com/errata/RHSA-2025:11849
This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2025:11884 https://access.redhat.com/errata/RHSA-2025:11884
This issue has been addressed in the following products: Red Hat Enterprise Linux 10 Via RHSA-2025:12064 https://access.redhat.com/errata/RHSA-2025:12064
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.4 Extended Update Support Via RHSA-2025:12416 https://access.redhat.com/errata/RHSA-2025:12416
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions Via RHSA-2025:12520 https://access.redhat.com/errata/RHSA-2025:12520
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions Via RHSA-2025:12523 https://access.redhat.com/errata/RHSA-2025:12523
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions Red Hat Enterprise Linux 8.8 Telecommunications Update Service Via RHSA-2025:12929 https://access.redhat.com/errata/RHSA-2025:12929
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.2 Advanced Update Support Via RHSA-2025:13576 https://access.redhat.com/errata/RHSA-2025:13576
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On Via RHSA-2025:13575 https://access.redhat.com/errata/RHSA-2025:13575
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions Red Hat Enterprise Linux 8.6 Telecommunications Update Service Via RHSA-2025:13577 https://access.redhat.com/errata/RHSA-2025:13577
This issue has been addressed in the following products: Red Hat OpenShift Container Platform 4.20 Via RHSA-2025:15397 https://access.redhat.com/errata/RHSA-2025:15397
This issue has been addressed in the following products: Red Hat OpenShift Container Platform 4.17 Via RHSA-2025:18218 https://access.redhat.com/errata/RHSA-2025:18218
This issue has been addressed in the following products: Red Hat OpenShift Container Platform 4.19 Via RHSA-2025:18217 https://access.redhat.com/errata/RHSA-2025:18217
This issue has been addressed in the following products: Red Hat OpenShift Container Platform 4.13 Via RHSA-2025:18240 https://access.redhat.com/errata/RHSA-2025:18240
This issue has been addressed in the following products: Red Hat OpenShift Container Platform 4.18 Via RHSA-2025:19046 https://access.redhat.com/errata/RHSA-2025:19046
This issue has been addressed in the following products: Red Hat OpenShift Container Platform 4.14 Via RHSA-2025:19041 https://access.redhat.com/errata/RHSA-2025:19041
This issue has been addressed in the following products: Red Hat OpenShift Container Platform 4.12 Via RHSA-2025:19894 https://access.redhat.com/errata/RHSA-2025:19894