CVE-2026-11721
Description
It is possible for an attacker's zone to respond to a query with an RRSIG that has a smaller number of labels than the zone in which the RRSIG is contained. This causes `named` to produce a wildcard name for a zone that is shorter than the attacker's zone, which can result in cache poisoning. For this attack to have any effect, the resolver under attack must have set `synth-from-dnssec yes;` (which is the default). This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1.
How to fix
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| isc bind | 9.11.0 ≤ v ≤ 9.18.50, 9.11.3 ≤ v ≤ 9.18.50, 9.20.0 ≤ v ≤ 9.20.24, 9.20.9 ≤ v ≤ 9.20.24, 9.21.0 ≤ v ≤ 9.21.23 | — |
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