CVE-2025-40780: ISC BIND 9

High severity, CVSS 8.6. EPSS: 0.5% chance of exploitation in the next 30 days.

In specific circumstances, due to a weakness in the Pseudo Random Number Generator (PRNG) that is used, it is possible for an attacker to predict the source port and query ID that BIND will use. This issue affects BIND 9 versions 9.16.0 through 9.16.50, 9.18.0 through 9.18.39, 9.20.0 through 9.20.13, 9.21.0 through 9.21.12, 9.16.8-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.39-S1, and 9.20.9-S1 through 9.20.13-S1.

Affected products

• ISC BIND 9: from 9.16.0, up to and including 9.16.50; from 9.18.0, up to and including 9.18.39; from 9.20.0, up to and including 9.20.13; from 9.21.0, up to and including 9.21.12; from 9.16.8-S1, up to and including 9.16.50-S1; from 9.18.11-S1, up to and including 9.18.39-S1; …

Published 2025-10-22. Last modified 2026-10-08.