CVE-2026-81563: CWE-401 Missing Release of Memory after Effective Lifetime in ISC BIND 9
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.
AI Analysis
Technical Summary
This vulnerability (CVE-2026-81563) in ISC BIND 9 arises from a missing release of memory after its effective lifetime (CWE-401). Specifically, when a BIND resolver encounters an SVCB/HTTPS AliasMode record that references 14 or more SVCB/HTTPS ServiceMode records, it may fail to properly free internal resources. This can cause resource exhaustion over time, ultimately blocking the resolver from performing new recursive lookups. The affected versions include 9.18.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, and their respective S1 variants as listed.
Potential Impact
The vulnerability can cause denial of service by exhausting internal resources of the BIND resolver, preventing it from performing new recursive DNS lookups. There is no impact on confidentiality or integrity reported. No known exploits in the wild have been identified.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch links are provided in the available data. Users should monitor ISC advisories for updates and consider limiting exposure to crafted SVCB/HTTPS records until a fix is available.
CVE-2026-81563: CWE-401 Missing Release of Memory after Effective Lifetime in ISC BIND 9
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.
CVSS v3.1
Score 7.5high
Affected software
ISC
BIND 9
pkg:deb/isc/bind9Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability (CVE-2026-81563) in ISC BIND 9 arises from a missing release of memory after its effective lifetime (CWE-401). Specifically, when a BIND resolver encounters an SVCB/HTTPS AliasMode record that references 14 or more SVCB/HTTPS ServiceMode records, it may fail to properly free internal resources. This can cause resource exhaustion over time, ultimately blocking the resolver from performing new recursive lookups. The affected versions include 9.18.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, and their respective S1 variants as listed.
Potential Impact
The vulnerability can cause denial of service by exhausting internal resources of the BIND resolver, preventing it from performing new recursive DNS lookups. There is no impact on confidentiality or integrity reported. No known exploits in the wild have been identified.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch links are provided in the available data. Users should monitor ISC advisories for updates and consider limiting exposure to crafted SVCB/HTTPS records until a fix is available.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- isc
- Date Reserved
- 2026-08-27T05:57:37.544Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6aaaa16f55bf5e2cf5b35d47
Added to database: 09/16/2026, 14:02:23 UTC
Last enriched: 09/16/2026, 14:16:44 UTC
Last updated: 09/17/2026, 03:22:34 UTC
Views: 12
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