# CVE-2026-5950: Unbounded resend loop in BIND 9 resolver CVE-2026-5950 is fixed in 20 products on 1 platform, first by bind9 1:9.20.18-1ubuntu2.1, released May 19, 2026. It is not reported as exploited. Patch Radar priority: Routine. - Web page: https://patchblox.com/security/cve/CVE-2026-5950 - Priority: Routine - CVSS: 5.3 (Moderate) - EPSS: 0.0066 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: May 19, 2026 - Weakness: Unchecked Input for Loop Condition - Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-5950 ## Description An unbounded resend loop vulnerability exists in the BIND 9 resolver state machine during bad-server handling, enabling a remote unauthenticated attacker to cause severe resource exhaustion by sending queries that trigger specific retry conditions. This issue affects BIND 9 versions 9.18.36 through 9.18.48, 9.20.8 through 9.20.22, 9.21.7 through 9.21.21, 9.18.36-S1 through 9.18.48-S1, and 9.20.9-S1 through 9.20.22-S1. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | bind amzn 2023 | 32:9.18.49-1.amzn2023.0.1 | [ALAS2023-2026-1755](https://patchblox.com/security/data/fix/linux/alas2023-2026-1755.md) | May 25, 2026 | | Linux | bind opensuse-leap 16.0 | 9.20.23-160000.1.1 | [OPENSUSE-SU-2026:21123-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21123-1.md) | Jun 20, 2026 | | Linux | bind sles 15.6 | 9.18.49-150600.3.26.1 | [SUSE-SU-2026:2676-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2676-1.md) | Jun 29, 2026 | | Linux | bind sles 15.7 | 9.20.23-150700.3.25.1 | [SUSE-SU-2026:2673-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2673-1.md) | Jul 2, 2026 | | Linux | bind sles 16.0 | 9.20.23-160000.1.1 | [SUSE-SU-2026:22198-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22198-1.md) | Jun 20, 2026 | | Linux | bind-chroot amzn 2023 | 32:9.18.49-1.amzn2023.0.1 | [ALAS2023-2026-1755](https://patchblox.com/security/data/fix/linux/alas2023-2026-1755.md) | May 25, 2026 | | Linux | bind-debuginfo amzn 2023 | 32:9.18.49-1.amzn2023.0.1 | [ALAS2023-2026-1755](https://patchblox.com/security/data/fix/linux/alas2023-2026-1755.md) | May 25, 2026 | | Linux | bind-debugsource amzn 2023 | 32:9.18.49-1.amzn2023.0.1 | [ALAS2023-2026-1755](https://patchblox.com/security/data/fix/linux/alas2023-2026-1755.md) | May 25, 2026 | | Linux | bind-devel amzn 2023 | 32:9.18.49-1.amzn2023.0.1 | [ALAS2023-2026-1755](https://patchblox.com/security/data/fix/linux/alas2023-2026-1755.md) | May 25, 2026 | | Linux | bind-dnssec-utils amzn 2023 | 32:9.18.49-1.amzn2023.0.1 | [ALAS2023-2026-1755](https://patchblox.com/security/data/fix/linux/alas2023-2026-1755.md) | May 25, 2026 | | Linux | bind-dnssec-utils-debuginfo amzn 2023 | 32:9.18.49-1.amzn2023.0.1 | [ALAS2023-2026-1755](https://patchblox.com/security/data/fix/linux/alas2023-2026-1755.md) | May 25, 2026 | | Linux | bind-doc amzn 2023 | 32:9.18.49-1.amzn2023.0.1 | [ALAS2023-2026-1755](https://patchblox.com/security/data/fix/linux/alas2023-2026-1755.md) | May 25, 2026 | | Linux | bind-libs amzn 2023 | 32:9.18.49-1.amzn2023.0.1 | [ALAS2023-2026-1755](https://patchblox.com/security/data/fix/linux/alas2023-2026-1755.md) | May 25, 2026 | | Linux | bind-libs-debuginfo amzn 2023 | 32:9.18.49-1.amzn2023.0.1 | [ALAS2023-2026-1755](https://patchblox.com/security/data/fix/linux/alas2023-2026-1755.md) | May 25, 2026 | | Linux | bind-license amzn 2023 | 32:9.18.49-1.amzn2023.0.1 | [ALAS2023-2026-1755](https://patchblox.com/security/data/fix/linux/alas2023-2026-1755.md) | May 25, 2026 | | Linux | bind-utils amzn 2023 | 32:9.18.49-1.amzn2023.0.1 | [ALAS2023-2026-1755](https://patchblox.com/security/data/fix/linux/alas2023-2026-1755.md) | May 25, 2026 | | Linux | bind-utils-debuginfo amzn 2023 | 32:9.18.49-1.amzn2023.0.1 | [ALAS2023-2026-1755](https://patchblox.com/security/data/fix/linux/alas2023-2026-1755.md) | May 25, 2026 | | Linux | bind9 Debian 12.15 (bookworm) | 1:9.18.49-1~deb12u2 | [DEBIAN-CVE-2026-5950](https://patchblox.com/security/data/fix/linux/debian-cve-2026-5950.md) | May 27, 2026 | | Linux | bind9 Debian 13.5 (trixie) | 1:9.20.23-1~deb13u1 | [DEBIAN-CVE-2026-5950](https://patchblox.com/security/data/fix/linux/debian-cve-2026-5950.md) | May 27, 2026 | | Linux | bind9 Debian 14 | 1:9.20.23-1 | [DEBIAN-CVE-2026-5950](https://patchblox.com/security/data/fix/linux/debian-cve-2026-5950.md) | May 27, 2026 | | Linux | bind9 Ubuntu 22.04.1 LTS (jammy) | 1:9.18.39-0ubuntu0.22.04.4 | [bind9 1:9.18.39-0ubuntu0.22.04.4](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-bind9-1-9.18.39-0ubuntu0.22.04.4.md) | May 27, 2026 | | Linux | bind9 Ubuntu 24.04.5 LTS (noble) | 1:9.18.39-0ubuntu0.24.04.5 | [bind9 1:9.18.39-0ubuntu0.24.04.5](https://patchblox.com/security/data/fix/linux/ubuntu-noble-bind9-1-9.18.39-0ubuntu0.24.04.5.md) | May 27, 2026 | | Linux | bind9 Ubuntu 25.10 (questing) | 1:9.20.11-1ubuntu2.4 | [bind9 1:9.20.11-1ubuntu2.4](https://patchblox.com/security/data/fix/linux/ubuntu-questing-bind9-1-9.20.11-1ubuntu2.4.md) | May 27, 2026 | | Linux | bind9 Ubuntu 26.04.1 LTS (resolute) | 1:9.20.18-1ubuntu2.1 | [bind9 1:9.20.18-1ubuntu2.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-bind9-1-9.20.18-1ubuntu2.1.md) | May 19, 2026 | | Linux | bind9-dnsutils Ubuntu 22.04.1 LTS (jammy) | 1:9.18.39-0ubuntu0.22.04.4 | [bind9-dnsutils 1:9.18.39-0ubuntu0.22.04.4](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-bind9-dnsutils-1-9.18.39-0ubuntu0.22.04.4.md) | May 27, 2026 | | Linux | bind9-dnsutils Ubuntu 24.04.5 LTS (noble) | 1:9.18.39-0ubuntu0.24.04.5 | [bind9-dnsutils 1:9.18.39-0ubuntu0.24.04.5](https://patchblox.com/security/data/fix/linux/ubuntu-noble-bind9-dnsutils-1-9.18.39-0ubuntu0.24.04.5.md) | May 27, 2026 | | Linux | bind9-dnsutils Ubuntu 25.10 (questing) | 1:9.20.11-1ubuntu2.4 | [bind9-dnsutils 1:9.20.11-1ubuntu2.4](https://patchblox.com/security/data/fix/linux/ubuntu-questing-bind9-dnsutils-1-9.20.11-1ubuntu2.4.md) | May 27, 2026 | | Linux | bind9-dnsutils Ubuntu 26.04.1 LTS (resolute) | 1:9.20.18-1ubuntu2.1 | [bind9-dnsutils 1:9.20.18-1ubuntu2.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-bind9-dnsutils-1-9.20.18-1ubuntu2.1.md) | May 19, 2026 | | Linux | bind9-host Ubuntu 22.04.1 LTS (jammy) | 1:9.18.39-0ubuntu0.22.04.4 | [bind9-host 1:9.18.39-0ubuntu0.22.04.4](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-bind9-host-1-9.18.39-0ubuntu0.22.04.4.md) | May 27, 2026 | | Linux | bind9-host Ubuntu 24.04.5 LTS (noble) | 1:9.18.39-0ubuntu0.24.04.5 | [bind9-host 1:9.18.39-0ubuntu0.24.04.5](https://patchblox.com/security/data/fix/linux/ubuntu-noble-bind9-host-1-9.18.39-0ubuntu0.24.04.5.md) | May 27, 2026 | | Linux | bind9-host Ubuntu 25.10 (questing) | 1:9.20.11-1ubuntu2.4 | [bind9-host 1:9.20.11-1ubuntu2.4](https://patchblox.com/security/data/fix/linux/ubuntu-questing-bind9-host-1-9.20.11-1ubuntu2.4.md) | May 27, 2026 | | Linux | bind9-host Ubuntu 26.04.1 LTS (resolute) | 1:9.20.18-1ubuntu2.1 | [bind9-host 1:9.20.18-1ubuntu2.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-bind9-host-1-9.20.18-1ubuntu2.1.md) | May 19, 2026 | | Linux | bind9-libs Ubuntu 22.04.1 LTS (jammy) | 1:9.18.39-0ubuntu0.22.04.4 | [bind9-libs 1:9.18.39-0ubuntu0.22.04.4](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-bind9-libs-1-9.18.39-0ubuntu0.22.04.4.md) | May 27, 2026 | | Linux | bind9-libs Ubuntu 24.04.5 LTS (noble) | 1:9.18.39-0ubuntu0.24.04.5 | [bind9-libs 1:9.18.39-0ubuntu0.24.04.5](https://patchblox.com/security/data/fix/linux/ubuntu-noble-bind9-libs-1-9.18.39-0ubuntu0.24.04.5.md) | May 27, 2026 | | Linux | bind9-libs Ubuntu 25.10 (questing) | 1:9.20.11-1ubuntu2.4 | [bind9-libs 1:9.20.11-1ubuntu2.4](https://patchblox.com/security/data/fix/linux/ubuntu-questing-bind9-libs-1-9.20.11-1ubuntu2.4.md) | May 27, 2026 | | Linux | bind9-libs Ubuntu 26.04.1 LTS (resolute) | 1:9.20.18-1ubuntu2.1 | [bind9-libs 1:9.20.18-1ubuntu2.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-bind9-libs-1-9.20.18-1ubuntu2.1.md) | May 19, 2026 | | Linux | bind9-utils Ubuntu 22.04.1 LTS (jammy) | 1:9.18.39-0ubuntu0.22.04.4 | [bind9-utils 1:9.18.39-0ubuntu0.22.04.4](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-bind9-utils-1-9.18.39-0ubuntu0.22.04.4.md) | May 27, 2026 | | Linux | bind9-utils Ubuntu 24.04.5 LTS (noble) | 1:9.18.39-0ubuntu0.24.04.5 | [bind9-utils 1:9.18.39-0ubuntu0.24.04.5](https://patchblox.com/security/data/fix/linux/ubuntu-noble-bind9-utils-1-9.18.39-0ubuntu0.24.04.5.md) | May 27, 2026 | | Linux | bind9-utils Ubuntu 25.10 (questing) | 1:9.20.11-1ubuntu2.4 | [bind9-utils 1:9.20.11-1ubuntu2.4](https://patchblox.com/security/data/fix/linux/ubuntu-questing-bind9-utils-1-9.20.11-1ubuntu2.4.md) | May 27, 2026 | | Linux | bind9-utils Ubuntu 26.04.1 LTS (resolute) | 1:9.20.18-1ubuntu2.1 | [bind9-utils 1:9.20.18-1ubuntu2.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-bind9-utils-1-9.20.18-1ubuntu2.1.md) | May 19, 2026 | | Linux | bind9utils Ubuntu 22.04.1 LTS (jammy) | 1:9.18.39-0ubuntu0.22.04.4 | [bind9utils 1:9.18.39-0ubuntu0.22.04.4](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-bind9utils-1-9.18.39-0ubuntu0.22.04.4.md) | May 27, 2026 | | Linux | bind9utils Ubuntu 24.04.5 LTS (noble) | 1:9.18.39-0ubuntu0.24.04.5 | [bind9utils 1:9.18.39-0ubuntu0.24.04.5](https://patchblox.com/security/data/fix/linux/ubuntu-noble-bind9utils-1-9.18.39-0ubuntu0.24.04.5.md) | May 27, 2026 | | Linux | dnsutils Ubuntu 22.04.1 LTS (jammy) | 1:9.18.39-0ubuntu0.22.04.4 | [dnsutils 1:9.18.39-0ubuntu0.22.04.4](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-dnsutils-1-9.18.39-0ubuntu0.22.04.4.md) | May 27, 2026 | | Linux | dnsutils Ubuntu 24.04.5 LTS (noble) | 1:9.18.39-0ubuntu0.24.04.5 | [dnsutils 1:9.18.39-0ubuntu0.24.04.5](https://patchblox.com/security/data/fix/linux/ubuntu-noble-dnsutils-1-9.18.39-0ubuntu0.24.04.5.md) | May 27, 2026 | --- Data as of 2026-11-08T00:53:09Z UTC. 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