CVE-2026-5950
Published:May 20, 2026
Updated:September 25, 2026
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.
Affected Packages
https://github.com/isc-projects/bind9.git (GITHUB):
Affected version(s) >=v9.21.7 <v9.21.22Fix Suggestion:
Update to version v9.21.22https://github.com/isc-projects/bind9.git (GITHUB):
Affected version(s) >=v9.20.8 <v9.20.23Fix Suggestion:
Update to version v9.20.23https://github.com/isc-projects/bind9.git (GITHUB):
Affected version(s) >=v9.18.36 <v9.18.49Fix Suggestion:
Update to version v9.18.49Related Resources (4)
Do you need more information?
Contact UsCVSS v4
Base Score:
6.9
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
LOW
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
5.3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
LOW
Weakness Type (CWE)
Unchecked Input for Loop Condition
EPSS
Base Score:
0.80