Is CVE-2026-19666 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-19666 being exploited in the wild.

How severe is CVE-2026-19666?

High severity, with a CVSS score of 7.5, published 16 September 2026.

Which products and versions are affected?

Isc Bind 9.11.0–9.18.50, 9.11.3-S1–9.18.50-S1, 9.20.0–9.20.27, 9.20.9-S1–9.20.27-S1, 9.21.0–9.21.25.

Is there a fix for CVE-2026-19666?

A patch was published on 2026-09-16: Patches released: BIND 9.18.51, 9.20.28, 9.20.28-S2, 9.21.26 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-19666 attacked?

It is attacked over the network, in a hosted service.

Am I affected by CVE-2026-19666?

Check whether you run Isc Bind at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-19666: ISC BIND dns64 malformed answer crash

CVE-2026-19666 · Severity: high · CVSS 7.5 · Published 2026-09-16

BIND is a widely-used DNS resolver software that translates domain names into IP addresses for internet connectivity. On resolvers configured with the dns64 feature (used for IPv6/IPv4 translation), a specially crafted malformed DNS response from an authoritative server can cause the BIND process to crash unexpectedly, resulting in a complete service outage and loss of DNS resolution capability for affected clients.

Technologies: Isc Bind. Vendors: Isc.

Quick answers

Is CVE-2026-19666 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-19666 being exploited in the wild.
How severe is CVE-2026-19666?: High severity, with a CVSS score of 7.5, published 16 September 2026.
Which products and versions are affected?: Isc Bind 9.11.0–9.18.50, 9.11.3-S1–9.18.50-S1, 9.20.0–9.20.27, 9.20.9-S1–9.20.27-S1, 9.21.0–9.21.25.
Is there a fix for CVE-2026-19666?: A patch was published on 2026-09-16: Patches released: BIND 9.18.51, 9.20.28, 9.20.28-S2, 9.21.26 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-19666 attacked?: It is attacked over the network, in a hosted service.
Am I affected by CVE-2026-19666?: Check whether you run Isc Bind at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

This is a denial-of-service vulnerability in BIND's dns64 functionality. When a resolver processes a malformed DNS answer from an authoritative server—specifically one that is malformed in a particular way—and dns64 is enabled, the named process crashes without proper error handling. The vulnerability is triggered by parsing a network-reachable response from an authoritative DNS server; no authentication or special client privileges are required. The attack vector is network-based, and an attacker can cause service disruption by controlling or spoofing responses from an authoritative server. Patches are available in BIND 9.18.51, 9.20.28, 9.20.28-S2, and 9.21.26.

Affected products

ISC BIND 9.11.0–9.18.50, 9.11.3-S1–9.18.50-S1, 9.20.0–9.20.27, 9.20.9-S1–9.20.27-S1, 9.21.0–9.21.25

Timeline

2026-09-16: disclosed
2026-09-16: patched: Patches released: BIND 9.18.51, 9.20.28, 9.20.28-S2, 9.21.26

References

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.