CVE-2026-5950

Unbounded resend loop in BIND 9 resolver

Published: May 20, 2026Updated: Jul 23, 2026 Sources: CVE List NVDCWE-606

5.3MEDIUM

Description

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.

No summary for this CVE yet.

CVSS Vector Breakdown

Exploitability

AV:NAttack Vector

Network

AC:LAttack Complexity

Low

PR:NPrivileges Required

None

UI:NUser Interaction

None

Scope

S:UScope

Unchanged

Impact

C:NConfidentiality

None

I:NIntegrity

None

A:LAvailability

Low

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Weaknesses

CWE-606

Affected Products

ISC

commercial·USaka internet systems consortium

bind

Networking Infrastructure

BIND 9

Networking Infrastructure

Exploitability

0 exploit sources identified

Exploit details including PoC links, Metasploit modules, and scanner templates are available after registration.

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Official Patch Available

Workaround Available

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References

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

downloads.isc.org

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

downloads.isc.org

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

downloads.isc.org

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