CVE-2026-19662: CWE-416 Use After Free in ISC BIND 9
An attacker may be able to cause a `named` resolver to abort. The attack requires inducing the victim resolver to send multiple queries for a DNSSEC-signed zone hosted by an authoritative server under the control of the attacker. If the auth responds with a particular sequence of crafted answers, and those answers arrive in a particular order with particular timing, the `named` resolver will encounter a use-after-free bug, and abort. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.27, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.27-S1.
AI Analysis
Technical Summary
CVE-2026-19662 is a use-after-free vulnerability (CWE-416) in ISC BIND 9's named resolver. An attacker controlling an authoritative DNS server for a DNSSEC-signed zone can induce the resolver to send multiple queries. If the attacker responds with a particular crafted sequence of DNS answers arriving in a specific order and timing, the resolver encounters a use-after-free bug leading to an abort of the named process. This vulnerability affects BIND 9 versions >=9.11.0 <=9.18.50, >=9.20.0 <=9.20.27, and their S1 variants within the same version ranges. The CVSS 3.1 vector indicates network attack vector, high attack complexity, no privileges required, no user interaction, unchanged scope, no confidentiality or integrity impact, but high impact on availability.
Potential Impact
The vulnerability causes the named DNS resolver to abort, resulting in a denial of service condition. There is no impact on confidentiality or integrity. The attack requires the attacker to control an authoritative DNS server for a DNSSEC-signed zone and to deliver crafted responses in a specific sequence and timing. No known exploits in the wild have been reported.
Mitigation Recommendations
Patch status is not yet confirmed — check the ISC vendor advisory for current remediation guidance. Until a patch is available, mitigate by avoiding queries to attacker-controlled DNSSEC-signed zones or restricting resolver access to trusted zones. Monitor ISC advisories for official fixes.
CVE-2026-19662: CWE-416 Use After Free in ISC BIND 9
Description
An attacker may be able to cause a `named` resolver to abort. The attack requires inducing the victim resolver to send multiple queries for a DNSSEC-signed zone hosted by an authoritative server under the control of the attacker. If the auth responds with a particular sequence of crafted answers, and those answers arrive in a particular order with particular timing, the `named` resolver will encounter a use-after-free bug, and abort. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.27, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.27-S1.
CVSS v3.1
Score 5.9medium
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
CVE-2026-19662 is a use-after-free vulnerability (CWE-416) in ISC BIND 9's named resolver. An attacker controlling an authoritative DNS server for a DNSSEC-signed zone can induce the resolver to send multiple queries. If the attacker responds with a particular crafted sequence of DNS answers arriving in a specific order and timing, the resolver encounters a use-after-free bug leading to an abort of the named process. This vulnerability affects BIND 9 versions >=9.11.0 <=9.18.50, >=9.20.0 <=9.20.27, and their S1 variants within the same version ranges. The CVSS 3.1 vector indicates network attack vector, high attack complexity, no privileges required, no user interaction, unchanged scope, no confidentiality or integrity impact, but high impact on availability.
Potential Impact
The vulnerability causes the named DNS resolver to abort, resulting in a denial of service condition. There is no impact on confidentiality or integrity. The attack requires the attacker to control an authoritative DNS server for a DNSSEC-signed zone and to deliver crafted responses in a specific sequence and timing. No known exploits in the wild have been reported.
Mitigation Recommendations
Patch status is not yet confirmed — check the ISC vendor advisory for current remediation guidance. Until a patch is available, mitigate by avoiding queries to attacker-controlled DNSSEC-signed zones or restricting resolver access to trusted zones. Monitor ISC advisories for official fixes.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- isc
- Date Reserved
- 2026-08-12T20:13:09.206Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6aaaa16f55bf5e2cf5b35d4b
Added to database: 09/16/2026, 14:02:23 UTC
Last enriched: 09/16/2026, 14:31:43 UTC
Last updated: 09/17/2026, 03:24:36 UTC
Views: 12
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