CVE-2026-81736: CWE-1050 Excessive Platform Resource Consumption within a Loop in ISC BIND 9
CVE-2026-81736 is a high-severity vulnerability in ISC BIND 9 that causes excessive CPU consumption when a resolver with cached SVCB/HTTPS AliasMode records is queried for the root of that tree. This issue affects multiple BIND 9 versions from 9.18.0 through 9.21.25 and their respective S1 variants. The vulnerability does not impact confidentiality or integrity but results in denial of service due to high CPU usage.
AI Analysis
Technical Summary
The vulnerability arises when a BIND 9 resolver that has cached a tree of SVCB/HTTPS AliasMode DNS records is queried for the root of that tree. The resolver spends disproportionate CPU time constructing the response, leading to excessive platform resource consumption within a loop (CWE-1050). This 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, and their S1 variants 9.18.11-S1 through 9.18.50-S1 and 9.20.9-S1 through 9.20.27-S1. The CVSS v3.1 score is 7.5, indicating high severity, with no confidentiality or integrity impact but significant availability impact.
Potential Impact
The vulnerability causes high CPU consumption on affected BIND 9 resolvers when processing specific DNS queries involving cached SVCB/HTTPS AliasMode records. This can degrade service availability due to resource exhaustion but does not affect data confidentiality or integrity. There are no known exploits in the wild at this time.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, consider limiting exposure of affected BIND 9 resolvers to untrusted queries or implementing rate limiting to mitigate potential resource exhaustion.
CVE-2026-81736: CWE-1050 Excessive Platform Resource Consumption within a Loop in ISC BIND 9
Description
CVE-2026-81736 is a high-severity vulnerability in ISC BIND 9 that causes excessive CPU consumption when a resolver with cached SVCB/HTTPS AliasMode records is queried for the root of that tree. This issue affects multiple BIND 9 versions from 9.18.0 through 9.21.25 and their respective S1 variants. The vulnerability does not impact confidentiality or integrity but results in denial of service due to high CPU usage.
CVSS v3.1
Score 7.5high
Affected software
ISC
BIND 9
pkg:github/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
The vulnerability arises when a BIND 9 resolver that has cached a tree of SVCB/HTTPS AliasMode DNS records is queried for the root of that tree. The resolver spends disproportionate CPU time constructing the response, leading to excessive platform resource consumption within a loop (CWE-1050). This 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, and their S1 variants 9.18.11-S1 through 9.18.50-S1 and 9.20.9-S1 through 9.20.27-S1. The CVSS v3.1 score is 7.5, indicating high severity, with no confidentiality or integrity impact but significant availability impact.
Potential Impact
The vulnerability causes high CPU consumption on affected BIND 9 resolvers when processing specific DNS queries involving cached SVCB/HTTPS AliasMode records. This can degrade service availability due to resource exhaustion but does not affect data confidentiality or integrity. There are no known exploits in the wild at this time.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, consider limiting exposure of affected BIND 9 resolvers to untrusted queries or implementing rate limiting to mitigate potential resource exhaustion.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- isc
- Date Reserved
- 2026-08-27T11:35:23.313Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6aaaa17455bf5e2cf5b35d69
Added to database: 09/16/2026, 14:02:28 UTC
Last enriched: 09/16/2026, 14:16:29 UTC
Last updated: 09/16/2026, 14:21:26 UTC
Views: 4
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