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CVE-2026-5950

Unbounded resend loop in BIND 9 resolver

Published: May 20, 2026Updated: May 20, 2026 Sources: CVE List NVD
NVD MITRE
5.3CVSS
MEDIUM

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.

EPSS Score
N/A
CISA KEV
Not in KEV
Exploits
0 Known
Remediation
Patch Available

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:NA:L
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

Weaknesses

CWE-606

Affected Products

BIND 9
ISC

Exploitability

0 exploit sources identified

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

View exploit details
Official Patch Available
Workaround Available

References

https://kb.isc.org/docs/cve-2026-5950
kb.isc.org
https://downloads.isc.org/isc/bind9/9.18.49
downloads.isc.org
https://downloads.isc.org/isc/bind9/9.20.23
downloads.isc.org
and 1 more references View all →

Timeline

Published
May 20, 2026
Last Updated
May 20, 2026

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