Unbounded resend loop in BIND 9 resolver_CVE-2026-5950

5.3 / 10

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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.

Basic Information

ID CVE-2026-5950

Source isc

Published May 20, 2026 at 13:10

Affected Product

Vendor ISC

Product BIND 9

Version 9.18.36

Affected Versions ISC BIND 9 9.18.36
ISC BIND 9 9.20.8
ISC BIND 9 9.21.7
ISC BIND 9 9.18.36-S1
ISC BIND 9 9.20.9-S1

CWE Classification

CWE-606

References

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    "published": "2026-05-20T13:10:19.989Z",
    "modified": "2026-05-20T13:10:19.989Z",
    "type": "cve",
    "title": "Unbounded resend loop in BIND 9 resolver",
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    "references": "https://kb.isc.org/docs/cve-2026-5950\nhttps://downloads.isc.org/isc/bind9/9.18.49\nhttps://downloads.isc.org/isc/bind9/9.20.23\nhttps://downloads.isc.org/isc/bind9/9.21.22",
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