ISC BIND 9.18.36 < 9.18.49 / 9.18.36-S1 < 9.18.49-S1 / 9.20.8 < 9.20.23 / 9.20.9-S1 < 9.20.23-S1 / 9.21.7 < 9.21.22 Vulnerability (cve-2026-5950)

medium Nessus Plugin ID 315734

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Synopsis

The remote name server is affected by a vulnerability vulnerability.

Description

The version of ISC BIND installed on the remote host is prior to tested version. It is, therefore, affected by a vulnerability as referenced in the cve-2026-5950 advisory.

- 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. (CVE-2026-5950)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Upgrade to ISC BIND version 9.18.49 / 9.18.49-S1 / 9.20.23 / 9.20.23-S1 / 9.21.22 or later.

Plugin Details

Severity: Medium

ID: 315734

File Name: bind9_92122_cve-2026-5950.nasl

Version: 1.3

Type: Remote

Family: DNS

Published: 5/20/2026

Updated: 5/26/2026

Configuration: Enable paranoid mode

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Low

Score: 2.2

CVSS v2

Risk Factor: Medium

Base Score: 5

Temporal Score: 3.7

Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P

CVSS Score Source: CVE-2026-5950

CVSS v3

Risk Factor: Medium

Base Score: 5.3

Temporal Score: 4.6

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/a:isc:bind

Required KB Items: Settings/ParanoidReport, bind/version

Exploit Ease: No known exploits are available

Patch Publication Date: 5/20/2026

Vulnerability Publication Date: 5/20/2026

Reference Information

CVE: CVE-2026-5950

IAVA: 2026-A-0498

Detections

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