Vulnerability · Published Sep 16, 2026 · Assigned by isc
CVE-2026-81563SVCB AliasMode additional-data error leaks qpcache references
High 7.5
In plain English
A high-severity memory leak in BIND 9 from ISC. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 47% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
A BIND resolver encountering an SVCB/HTTPS AliasMode record referencing 14 or more SVCB/HTTPS ServiceMode records may fail to properly deallocate internal resources. If this happens repeatedly, resource exhaustion will eventually prevent the resolver from performing new recursive lookups. This issue affects BIND 9 versions 9.18.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, 9.18.11-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.27-S1.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:10 | bind | 32:9.18.33-15.el10_2.12 | ALSA-2026:75577 |
| AlmaLinux:10 | bind-chroot | 32:9.18.33-15.el10_2.12 | ALSA-2026:75577 |
| AlmaLinux:10 | bind-devel | 32:9.18.33-15.el10_2.12 | ALSA-2026:75577 |
| AlmaLinux:10 | bind-dnssec-utils | 32:9.18.33-15.el10_2.12 | ALSA-2026:75577 |
| AlmaLinux:10 | bind-doc | 32:9.18.33-15.el10_2.12 | ALSA-2026:75577 |
| AlmaLinux:10 | bind-libs | 32:9.18.33-15.el10_2.12 | ALSA-2026:75577 |
| AlmaLinux:10 | bind-license | 32:9.18.33-15.el10_2.12 | ALSA-2026:75577 |
| AlmaLinux:10 | bind-utils | 32:9.18.33-15.el10_2.12 | ALSA-2026:75577 |
| AlmaLinux:9 | bind9.18 | 32:9.18.29-14.el9_8.10 | ALSA-2026:75578 |
| AlmaLinux:9 | bind9.18-chroot | 32:9.18.29-14.el9_8.10 | ALSA-2026:75578 |
| AlmaLinux:9 | bind9.18-devel | 32:9.18.29-14.el9_8.10 | ALSA-2026:75578 |
| AlmaLinux:9 | bind9.18-dnssec-utils | 32:9.18.29-14.el9_8.10 | ALSA-2026:75578 |
| AlmaLinux:9 | bind9.18-doc | 32:9.18.29-14.el9_8.10 | ALSA-2026:75578 |
| AlmaLinux:9 | bind9.18-libs | 32:9.18.29-14.el9_8.10 | ALSA-2026:75578 |
| AlmaLinux:9 | bind9.18-utils | 32:9.18.29-14.el9_8.10 | ALSA-2026:75578 |
| Alpine:v3.22 | bind | 9.20.29-r0 | ALPINE-CVE-2026-81563 |
| Alpine:v3.23 | bind | 9.20.29-r0 | ALPINE-CVE-2026-81563 |
| Alpine:v3.24 | bind | 9.20.29-r0 | ALPINE-CVE-2026-81563 |
| Debian:12 | bind9 | 1:9.18.49-1~deb12u3 | DEBIAN-CVE-2026-81563 |
| Debian:13 | bind9 | 1:9.20.29-1~deb13u1 | DEBIAN-CVE-2026-81563 |
| Debian:14 | bind9 | 1:9.20.29-1 | DEBIAN-CVE-2026-81563 |
| Rocky Linux:10 | bind | 2:9.18.33-15.el10_2.12 | RLSA-2026:75577 |
| Rocky Linux:9 | bind9.18 | 2:9.18.29-14.el9_8.10 | RLSA-2026:75578 |
| Ubuntu:22.04:LTS | bind9 | 1:9.18.39-0ubuntu0.22.04.7 | UBUNTU-CVE-2026-81563 |
| Ubuntu:22.04:LTS | bind9 | 1:9.18.39-0ubuntu0.22.04.7 | USN-8929-1 |
| Ubuntu:22.04:LTS | bind9 | 1:9.18.39-0ubuntu0.22.04.8 | USN-8969-1 |
| Ubuntu:24.04:LTS | bind9 | 1:9.18.39-0ubuntu0.24.04.8 | USN-8929-1 |
| Ubuntu:24.04:LTS | bind9 | 1:9.18.39-0ubuntu0.24.04.9 | USN-8969-1 |
| Ubuntu:24.04:LTS | bind9 | 1:9.18.39-0ubuntu0.24.04.8 | UBUNTU-CVE-2026-81563 |
| Ubuntu:26.04:LTS | bind9 | 1:9.20.24-1ubuntu0.4 | UBUNTU-CVE-2026-81563 |
| Ubuntu:26.04:LTS | bind9 | 1:9.20.24-1ubuntu0.4 | USN-8929-1 |
| Ubuntu:26.04:LTS | bind9 | 1:9.20.24-1ubuntu0.5 | USN-8969-1 |
| Ubuntu:26.10 | bind9 | 1:9.20.24-1ubuntu3.1 | UBUNTU-CVE-2026-81563 |
| Ubuntu:26.10 | bind9 | 1:9.20.24-1ubuntu3.1 | USN-8969-1 |
| Ubuntu:22.04:LTS | bind9-libs | no fix listed | UBUNTU-CVE-2026-81563 |
| Ubuntu:24.04:LTS | isc-dhcp | no fix listed | UBUNTU-CVE-2026-81563 |
| Ubuntu:26.04:LTS | isc-dhcp | no fix listed | UBUNTU-CVE-2026-81563 |
Affected products (as reported)
Weakness: CWE-401 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
References
- CVE-2026-81563 vendor-advisory
- https://downloads.isc.org/isc/bind9/9.20.29 patch
- https://downloads.isc.org/isc/bind9/9.21.26 patch