CVE-2026-5950

MEDIUM5.3

Unbounded resend loop in BIND 9 resolver

Published May 20, 2026

Modified 1 months ago

Details

An unbounded resend loop vulnerability exists in the BIND 9 resolver state machine during bad-server handling, enabling a remote unauthenticated attacker to cause severe resource exhaustion by sending queries that trigger specific retry conditions. This issue affects BIND 9 versions 9.18.36 through 9.18.48, 9.20.8 through 9.20.22, 9.21.7 through 9.21.21, 9.18.36-S1 through 9.18.48-S1, and 9.20.9-S1 through 9.20.22-S1.

References

FIX

https://downloads.isc.org/isc/bind9/9.18.49

FIX

https://downloads.isc.org/isc/bind9/9.20.23

FIX

https://downloads.isc.org/isc/bind9/9.21.22

ADVISORY

https://kb.isc.org/docs/cve-2026-5950

ADVISORY

https://www.cve.org/CVERecord?id=CVE-2026-5950

CVSS Analysis