ISC BIND 9 up to 9.20.27-S1 dns64 input validation

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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7.3$0-$5k0.44

Summaryinfo

A vulnerability, which was classified as critical, has been found in ISC BIND 9 up to 9.18.50/9.20.27/9.21.25/9.18.50-S1/9.20.27-S1. This issue affects some unknown processing of the component dns64. The manipulation leads to input validation. This vulnerability is traded as CVE-2026-19666. It is possible to initiate the attack remotely. There is no exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in ISC BIND 9 up to 9.18.50/9.20.27/9.21.25/9.18.50-S1/9.20.27-S1 and classified as critical. This issue affects an unknown functionality of the component dns64. The manipulation with an unknown input leads to a input validation vulnerability. Using CWE to declare the problem leads to CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. Impacted is availability. The summary by CVE is:

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.

It is possible to read the advisory at kb.isc.org. The identification of this vulnerability is CVE-2026-19666 since 08/12/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 09/16/2026).

Upgrading to version 9.18.50-S1, 9.20.27-S1 or 9.21.25 eliminates this vulnerability.

Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.5
VulDB Meta Temp Score: 7.3

VulDB Base Score: 7.5
VulDB Temp Score: 7.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.5
CNA Vector (isc): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Input validation
CWE: CWE-20
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: BIND 9 9.18.50-S1/9.20.27-S1/9.21.25

Timelineinfo

08/12/2026 CVE reserved
09/16/2026 +35 days Advisory disclosed
09/16/2026 +0 days VulDB entry created
09/16/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: isc.org

Advisory: kb.isc.org
Status: Confirmed

CVE: CVE-2026-19666 (🔒)
GCVE (CVE): GCVE-0-2026-19666
GCVE (VulDB): GCVE-100-405959

Entryinfo

Created: 09/16/2026 16:43
Changes: 09/16/2026 16:43 (64)
Complete: 🔍
Cache ID: 216::103

Be aware that VulDB is the high quality source for vulnerability data.

Discussion

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