CVE-2026-19666: CWE-416 Use After Free in ISC BIND 9
On a resolver configured to use ``dns64``, if an applicable answer from the authoritative server is malformed in a specific way, the resolver `named` process will exit unexpectedly. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.27-S1.
AI Analysis
Technical Summary
This vulnerability (CWE-416) occurs in ISC BIND 9 resolvers configured to use dns64. When the resolver receives a malformed response from an authoritative DNS server in a particular way, it triggers a use-after-free condition causing the named process to crash. The affected versions include 9.11.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, and their S1 variants within these ranges. The CVSS 3.1 score is 7.5 (high), reflecting network attack vector, low complexity, no privileges required, no user interaction, unchanged scope, no confidentiality or integrity impact, but high availability impact.
Potential Impact
Successful exploitation causes the named resolver process to exit unexpectedly, resulting in denial of service. There is no impact on confidentiality or integrity according to the CVSS vector. No known exploits are reported in the wild at this time.
Mitigation Recommendations
Patch status is not yet confirmed — check the ISC vendor advisory for current remediation guidance. Until a patch is available, consider disabling dns64 or applying any recommended workarounds from ISC. Monitor ISC advisories for official fixes.
CVE-2026-19666: CWE-416 Use After Free in ISC BIND 9
Description
On a resolver configured to use ``dns64``, if an applicable answer from the authoritative server is malformed in a specific way, the resolver `named` process will exit unexpectedly. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, 9.11.3-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: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
This vulnerability (CWE-416) occurs in ISC BIND 9 resolvers configured to use dns64. When the resolver receives a malformed response from an authoritative DNS server in a particular way, it triggers a use-after-free condition causing the named process to crash. The affected versions include 9.11.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, and their S1 variants within these ranges. The CVSS 3.1 score is 7.5 (high), reflecting network attack vector, low complexity, no privileges required, no user interaction, unchanged scope, no confidentiality or integrity impact, but high availability impact.
Potential Impact
Successful exploitation causes the named resolver process to exit unexpectedly, resulting in denial of service. There is no impact on confidentiality or integrity according to the CVSS vector. No known exploits are reported in the wild at this time.
Mitigation Recommendations
Patch status is not yet confirmed — check the ISC vendor advisory for current remediation guidance. Until a patch is available, consider disabling dns64 or applying any recommended workarounds from ISC. Monitor ISC advisories for official fixes.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- isc
- Date Reserved
- 2026-08-12T20:26:23.829Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6aaaa87255bf5e2cf5bb9887
Added to database: 09/16/2026, 14:32:18 UTC
Last enriched: 09/16/2026, 14:46:49 UTC
Last updated: 09/17/2026, 03:07:18 UTC
Views: 7
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