CVE-2026-11721

Summary

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.

Affected Software

VendorProductVersion RangeStatus
ISCBIND 99.11.0 <= 9.18.50affected
ISCBIND 99.20.0 <= 9.20.24affected
ISCBIND 99.21.0 <= 9.21.23affected
ISCBIND 99.11.3-S1 <= 9.18.50-S1affected
ISCBIND 99.20.9-S1 <= 9.20.24-S1affected

Weaknesses

  • CWE-1284: CWE-1284 Improper Validation of Specified Quantity in Input

Workarounds

No workarounds known.

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: yes
    • Technical Impact: partial

References