High (7.5). EPSS 2.1% chance of exploitation in the next 30 days.
If a server hosts a zone containing a "KEY" Resource Record, or a resolver DNSSEC-validates a "KEY" Resource Record from a DNSSEC-signed domain in cache, a client can exhaust resolver CPU resources by sending a stream of SIG(0) signed requests.
This issue affects BIND 9 versions 9.0.0 through 9.11.37, 9.16.0 through 9.16.50, 9.18.0 through 9.18.27, 9.19.0 through 9.19.24, 9.9.3-S1 through 9.11.37-S1, 9.16.8-S1 through 9.16.49-S1, and 9.18.11-S1 through 9.18.27-S1.
Severity
CVSS 3.1
7.5 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS
2.1% chance of exploitation in the next 30 days; higher than 81% of CVEs (scores of 2026-10-31)