ISC BIND 9.20.0 < 9.20.11 / 9.20.9-S1 < 9.20.11-S1 / 9.21.0 < 9.21.10 Assertion Failure (cve-2025-40777)

high Nessus Plugin ID 298820

Synopsis

The remote name server is affected by an assertion failure 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-2025-40777 advisory.

- If a `named` caching resolver is configured with `serve-stale-enable` `yes`, and with `stale-answer- client-timeout` set to `0` (the only allowable value other than `disabled`), and if the resolver, in the process of resolving a query, encounters a CNAME chain involving a specific combination of cached or authoritative records, the daemon will abort with an assertion failure. This issue affects BIND 9 versions 9.20.0 through 9.20.10, 9.21.0 through 9.21.9, and 9.20.9-S1 through 9.20.10-S1. (CVE-2025-40777)

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 9.20.11 / 9.20.11-S1 / 9.21.10 or later.

Plugin Details

Severity: High

ID: 298820

File Name: bind9_92110_cve-2025-40777.nasl

Version: 1.1

Type: remote

Family: DNS

Published: 2/12/2026

Updated: 2/12/2026

Configuration: Enable paranoid mode

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3.6

CVSS v2

Risk Factor: High

Base Score: 7.8

Temporal Score: 5.8

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

CVSS Score Source: CVE-2025-40777

CVSS v3

Risk Factor: High

Base Score: 7.5

Temporal Score: 6.5

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

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

Vulnerability Information

CPE: cpe:/a:isc:bind

Required KB Items: bind/version, Settings/ParanoidReport

Exploit Ease: No known exploits are available

Patch Publication Date: 7/16/2025

Vulnerability Publication Date: 7/16/2025

Reference Information

CVE: CVE-2025-40777

Detections

Analytics