CVE-2026-11721CWE-1284

Cache poisoning possible with label count discrepancy, RRSIG, and wildcards

High · published July 22, 2026

CVSS v3.1
7.5
EPSS
0%
Percentile
32.6
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
7.5 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
CVSS v4.0
Not supplied
EPSS
0.00395 · 32.6th percentile
Weakness
CWE-1284 · Improper Validation of Specified Quantity in Input
Published
2026-07-22T14:13Z
EPSS history
Timeline
  • 22 JUL 14:13Z
    Cache poisoning possible with label count discrepancy, RRSIG, and wildcards
    cvelistv5