# CVE-2026-42960: Possible cache poisoning via promiscuous records for the authority section CVE-2026-42960 is fixed in 16 products on 1 platform, first by libunbound2 1.6.7-1ubuntu2.6+esm4, released May 19, 2026. It is not reported as exploited. Patch Radar priority: High. - Web page: https://patchblox.com/security/cve/CVE-2026-42960 - Priority: High - CVSS: 10.0 (Moderate) - EPSS: 0.0026 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: May 19, 2026 - Weakness: Acceptance of Extraneous Untrusted Data With Trusted Data - Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42960 ## Description NLnet Labs Unbound up to and including version 1.25.0 is vulnerable to poisoning via promiscuous records for the authority section. Promiscuous RRSets that complement DNS replies in the authority section can be used to trick Unbound to cache such records. If an adversary is able to attach such records in a reply (i.e., spoofed packet, fragmentation attack) he would be able to poison Unbound's cache. A malicious actor can exploit the possible poisonous effect by injecting RRSets other than NS that are also accompanied by address records in a reply, for example MX. This could be achieved by trying to spoof a reply packet or fragmentation attacks. Unbound would then accept the relative address records in the additional section and cache them if the authority RRSet has enough trust at this point, i.e., in-zone data for the delegation point. Unbound 1.25.1 contains a patch with a fix that disregards address records from the additional section if they are not explicitly relevant only to authority NS records, mitigating the possible poison effect. This is a complement fix to CVE-2025-11411. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | libunbound2 Ubuntu 18.04.6 LTS (bionic) | 1.6.7-1ubuntu2.6+esm4 | [libunbound2 1.6.7-1ubuntu2.6+esm4](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libunbound2-1.6.7-1ubuntu2.6-esm4.md) | May 19, 2026 | | Linux | libunbound8 Ubuntu 20.04 LTS (focal) | 1.9.4-2ubuntu1.11+esm1 | [libunbound8 1.9.4-2ubuntu1.11+esm1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libunbound8-1.9.4-2ubuntu1.11-esm1.md) | May 19, 2026 | | Linux | libunbound8 Ubuntu 22.04.1 LTS (jammy) | 1.13.1-1ubuntu5.15 | [libunbound8 1.13.1-1ubuntu5.15](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libunbound8-1.13.1-1ubuntu5.15.md) | May 27, 2026 | | Linux | libunbound8 Ubuntu 24.04.5 LTS (noble) | 1.19.2-1ubuntu3.8 | [libunbound8 1.19.2-1ubuntu3.8](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libunbound8-1.19.2-1ubuntu3.8.md) | May 27, 2026 | | Linux | libunbound8 Ubuntu 25.10 (questing) | 1.22.0-2ubuntu2.3 | [libunbound8 1.22.0-2ubuntu2.3](https://patchblox.com/security/data/fix/linux/ubuntu-questing-libunbound8-1.22.0-2ubuntu2.3.md) | May 27, 2026 | | Linux | libunbound8 Ubuntu 26.04.1 LTS (resolute) | 1.24.2-1ubuntu2.1 | [libunbound8 1.24.2-1ubuntu2.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libunbound8-1.24.2-1ubuntu2.1.md) | May 19, 2026 | | Linux | python-unbound Ubuntu 18.04.6 LTS (bionic) | 1.6.7-1ubuntu2.6+esm4 | [python-unbound 1.6.7-1ubuntu2.6+esm4](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-python-unbound-1.6.7-1ubuntu2.6-esm4.md) | May 19, 2026 | | Linux | python-unbound Ubuntu 20.04 LTS (focal) | 1.9.4-2ubuntu1.11+esm1 | [python-unbound 1.9.4-2ubuntu1.11+esm1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-python-unbound-1.9.4-2ubuntu1.11-esm1.md) | May 19, 2026 | | Linux | python3-unbound Ubuntu 18.04.6 LTS (bionic) | 1.6.7-1ubuntu2.6+esm4 | [python3-unbound 1.6.7-1ubuntu2.6+esm4](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-python3-unbound-1.6.7-1ubuntu2.6-esm4.md) | May 19, 2026 | | Linux | python3-unbound Ubuntu 20.04 LTS (focal) | 1.9.4-2ubuntu1.11+esm1 | [python3-unbound 1.9.4-2ubuntu1.11+esm1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-python3-unbound-1.9.4-2ubuntu1.11-esm1.md) | May 19, 2026 | | Linux | python3-unbound Ubuntu 22.04.1 LTS (jammy) | 1.13.1-1ubuntu5.15 | [python3-unbound 1.13.1-1ubuntu5.15](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-python3-unbound-1.13.1-1ubuntu5.15.md) | May 27, 2026 | | Linux | python3-unbound Ubuntu 24.04.5 LTS (noble) | 1.19.2-1ubuntu3.8 | [python3-unbound 1.19.2-1ubuntu3.8](https://patchblox.com/security/data/fix/linux/ubuntu-noble-python3-unbound-1.19.2-1ubuntu3.8.md) | May 27, 2026 | | Linux | python3-unbound Ubuntu 25.10 (questing) | 1.22.0-2ubuntu2.3 | [python3-unbound 1.22.0-2ubuntu2.3](https://patchblox.com/security/data/fix/linux/ubuntu-questing-python3-unbound-1.22.0-2ubuntu2.3.md) | May 27, 2026 | | Linux | python3-unbound Ubuntu 26.04.1 LTS (resolute) | 1.24.2-1ubuntu2.1 | [python3-unbound 1.24.2-1ubuntu2.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-python3-unbound-1.24.2-1ubuntu2.1.md) | May 19, 2026 | | Linux | python3-unbound amzn 2023 | 1.17.1-1.amzn2023.0.12 | [ALAS2023-2026-1756](https://patchblox.com/security/data/fix/linux/alas2023-2026-1756.md) | May 25, 2026 | | Linux | python3-unbound-debuginfo amzn 2023 | 1.17.1-1.amzn2023.0.12 | [ALAS2023-2026-1756](https://patchblox.com/security/data/fix/linux/alas2023-2026-1756.md) | May 25, 2026 | | Linux | unbound Debian 13.5 (trixie) | 1.22.0-2+deb13u3 | [DEBIAN-CVE-2026-42960](https://patchblox.com/security/data/fix/linux/debian-cve-2026-42960.md) | May 27, 2026 | | Linux | unbound Debian 14 | 1.25.1-1 | [DEBIAN-CVE-2026-42960](https://patchblox.com/security/data/fix/linux/debian-cve-2026-42960.md) | May 27, 2026 | | Linux | unbound Ubuntu 18.04.6 LTS (bionic) | 1.6.7-1ubuntu2.6+esm4 | [unbound 1.6.7-1ubuntu2.6+esm4](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-unbound-1.6.7-1ubuntu2.6-esm4.md) | May 19, 2026 | | Linux | unbound Ubuntu 20.04 LTS (focal) | 1.9.4-2ubuntu1.11+esm1 | [unbound 1.9.4-2ubuntu1.11+esm1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-unbound-1.9.4-2ubuntu1.11-esm1.md) | May 19, 2026 | | Linux | unbound Ubuntu 22.04.1 LTS (jammy) | 1.13.1-1ubuntu5.15 | [unbound 1.13.1-1ubuntu5.15](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-unbound-1.13.1-1ubuntu5.15.md) | May 27, 2026 | | Linux | unbound Ubuntu 24.04.5 LTS (noble) | 1.19.2-1ubuntu3.8 | [unbound 1.19.2-1ubuntu3.8](https://patchblox.com/security/data/fix/linux/ubuntu-noble-unbound-1.19.2-1ubuntu3.8.md) | May 27, 2026 | | Linux | unbound Ubuntu 25.10 (questing) | 1.22.0-2ubuntu2.3 | [unbound 1.22.0-2ubuntu2.3](https://patchblox.com/security/data/fix/linux/ubuntu-questing-unbound-1.22.0-2ubuntu2.3.md) | May 27, 2026 | | Linux | unbound Ubuntu 26.04.1 LTS (resolute) | 1.24.2-1ubuntu2.1 | [unbound 1.24.2-1ubuntu2.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-unbound-1.24.2-1ubuntu2.1.md) | May 19, 2026 | | Linux | unbound amzn 2023 | 1.17.1-1.amzn2023.0.12 | [ALAS2023-2026-1756](https://patchblox.com/security/data/fix/linux/alas2023-2026-1756.md) | May 25, 2026 | | Linux | unbound opensuse-leap 16.0 | 1.24.1-160000.2.1 | [OPENSUSE-SU-2026:21083-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21083-1.md) | Jun 18, 2026 | | Linux | unbound sles 16.0 | 1.24.1-160000.2.1 | [SUSE-SU-2026:22160-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22160-1.md) | Jun 18, 2026 | | Linux | unbound-anchor Ubuntu 18.04.6 LTS (bionic) | 1.6.7-1ubuntu2.6+esm4 | [unbound-anchor 1.6.7-1ubuntu2.6+esm4](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-unbound-anchor-1.6.7-1ubuntu2.6-esm4.md) | May 19, 2026 | | Linux | unbound-anchor Ubuntu 20.04 LTS (focal) | 1.9.4-2ubuntu1.11+esm1 | [unbound-anchor 1.9.4-2ubuntu1.11+esm1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-unbound-anchor-1.9.4-2ubuntu1.11-esm1.md) | May 19, 2026 | | Linux | unbound-anchor Ubuntu 22.04.1 LTS (jammy) | 1.13.1-1ubuntu5.15 | [unbound-anchor 1.13.1-1ubuntu5.15](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-unbound-anchor-1.13.1-1ubuntu5.15.md) | May 27, 2026 | | Linux | unbound-anchor Ubuntu 24.04.5 LTS (noble) | 1.19.2-1ubuntu3.8 | [unbound-anchor 1.19.2-1ubuntu3.8](https://patchblox.com/security/data/fix/linux/ubuntu-noble-unbound-anchor-1.19.2-1ubuntu3.8.md) | May 27, 2026 | | Linux | unbound-anchor Ubuntu 25.10 (questing) | 1.22.0-2ubuntu2.3 | [unbound-anchor 1.22.0-2ubuntu2.3](https://patchblox.com/security/data/fix/linux/ubuntu-questing-unbound-anchor-1.22.0-2ubuntu2.3.md) | May 27, 2026 | | Linux | unbound-anchor Ubuntu 26.04.1 LTS (resolute) | 1.24.2-1ubuntu2.1 | [unbound-anchor 1.24.2-1ubuntu2.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-unbound-anchor-1.24.2-1ubuntu2.1.md) | May 19, 2026 | | Linux | unbound-anchor amzn 2023 | 1.17.1-1.amzn2023.0.12 | [ALAS2023-2026-1756](https://patchblox.com/security/data/fix/linux/alas2023-2026-1756.md) | May 25, 2026 | | Linux | unbound-anchor-debuginfo amzn 2023 | 1.17.1-1.amzn2023.0.12 | [ALAS2023-2026-1756](https://patchblox.com/security/data/fix/linux/alas2023-2026-1756.md) | May 25, 2026 | | Linux | unbound-debuginfo amzn 2023 | 1.17.1-1.amzn2023.0.12 | [ALAS2023-2026-1756](https://patchblox.com/security/data/fix/linux/alas2023-2026-1756.md) | May 25, 2026 | | Linux | unbound-debugsource amzn 2023 | 1.17.1-1.amzn2023.0.12 | [ALAS2023-2026-1756](https://patchblox.com/security/data/fix/linux/alas2023-2026-1756.md) | May 25, 2026 | | Linux | unbound-devel amzn 2023 | 1.17.1-1.amzn2023.0.12 | [ALAS2023-2026-1756](https://patchblox.com/security/data/fix/linux/alas2023-2026-1756.md) | May 25, 2026 | | Linux | unbound-host Ubuntu 18.04.6 LTS (bionic) | 1.6.7-1ubuntu2.6+esm4 | [unbound-host 1.6.7-1ubuntu2.6+esm4](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-unbound-host-1.6.7-1ubuntu2.6-esm4.md) | May 19, 2026 | | Linux | unbound-host Ubuntu 20.04 LTS (focal) | 1.9.4-2ubuntu1.11+esm1 | [unbound-host 1.9.4-2ubuntu1.11+esm1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-unbound-host-1.9.4-2ubuntu1.11-esm1.md) | May 19, 2026 | | Linux | unbound-host Ubuntu 22.04.1 LTS (jammy) | 1.13.1-1ubuntu5.15 | [unbound-host 1.13.1-1ubuntu5.15](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-unbound-host-1.13.1-1ubuntu5.15.md) | May 27, 2026 | | Linux | unbound-host Ubuntu 24.04.5 LTS (noble) | 1.19.2-1ubuntu3.8 | [unbound-host 1.19.2-1ubuntu3.8](https://patchblox.com/security/data/fix/linux/ubuntu-noble-unbound-host-1.19.2-1ubuntu3.8.md) | May 27, 2026 | | Linux | unbound-host Ubuntu 25.10 (questing) | 1.22.0-2ubuntu2.3 | [unbound-host 1.22.0-2ubuntu2.3](https://patchblox.com/security/data/fix/linux/ubuntu-questing-unbound-host-1.22.0-2ubuntu2.3.md) | May 27, 2026 | | Linux | unbound-host Ubuntu 26.04.1 LTS (resolute) | 1.24.2-1ubuntu2.1 | [unbound-host 1.24.2-1ubuntu2.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-unbound-host-1.24.2-1ubuntu2.1.md) | May 19, 2026 | | Linux | unbound-libs amzn 2023 | 1.17.1-1.amzn2023.0.12 | [ALAS2023-2026-1756](https://patchblox.com/security/data/fix/linux/alas2023-2026-1756.md) | May 25, 2026 | | Linux | unbound-libs-debuginfo amzn 2023 | 1.17.1-1.amzn2023.0.12 | [ALAS2023-2026-1756](https://patchblox.com/security/data/fix/linux/alas2023-2026-1756.md) | May 25, 2026 | | Linux | unbound-utils amzn 2023 | 1.17.1-1.amzn2023.0.12 | [ALAS2023-2026-1756](https://patchblox.com/security/data/fix/linux/alas2023-2026-1756.md) | May 25, 2026 | | Linux | unbound-utils-debuginfo amzn 2023 | 1.17.1-1.amzn2023.0.12 | [ALAS2023-2026-1756](https://patchblox.com/security/data/fix/linux/alas2023-2026-1756.md) | May 25, 2026 | --- Data as of 2026-11-10T07:50:38Z UTC. 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