CVE-2026-81563
SVCB AliasMode additional-data error leaks qpcache references
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.
INFO
Published Date :
Sept. 16, 2026, 2:17 p.m.
Last Modified :
Sept. 16, 2026, 7:27 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update BIND to a patched version.
- Ensure SVCB record references are managed correctly.
- Monitor resolver resource utilization.
- Restart the resolver service if necessary.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-81563.
| URL | Resource |
|---|---|
| https://downloads.isc.org/isc/bind9/9.20.29 | |
| https://downloads.isc.org/isc/bind9/9.21.26 | |
| https://kb.isc.org/docs/cve-2026-81563 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-81563 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-81563
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-81563 vulnerability anywhere in the article.
-
The Hacker News
BIND 9 Update Fixes 14 Flaws, Including an Unauthenticated Crash Over DNS-over-HTTPS
The Internet Systems Consortium (ISC) has released BIND 9.20.29 and 9.21.26 to fix fourteen security flaws it disclosed on 16 September in BIND 9, its open-source DNS server software. One of them affe ... Read more
The following table lists the changes that have been made to the
CVE-2026-81563 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Sep. 16, 2026
Action Type Old Value New Value Added 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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-401 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/81xxx/CVE-2026-81563.json">CVE-2026-81563</a> Added Reference https://downloads.isc.org/isc/bind9/9.20.29 Added Reference https://downloads.isc.org/isc/bind9/9.21.26 Added Reference https://kb.isc.org/docs/cve-2026-81563