Reachable assertion in ISC BIND - CVE-2025-40775

Vulnerability identifier: #VU109620

CSH Severity: Medium

CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2025-40775

CWE-ID: CWE-617

Exploitation vector: Remote access

Exploit availability: Public exploit is available

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a reachable assertion when handling transaction signature (TSIG) in incoming DNS messages. A remote attacker can send specially crafted DNS messages to the affected server and perform a denial of service (DoS) attack.

ISC BIND
Arch Linux
SUSE Linux Enterprise Desktop 15
SUSE Linux Enterprise Real Time 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Server for SAP Applications 15
Basesystem Module
Server Applications Module
Ubuntu
bind9 (Ubuntu package)
bind
bind-utils-debuginfo
bind-debugsource
bind-utils
bind-debuginfo
bind-doc

Install updates from vendor's website.

ISC BIND - addressed in versions 9.20.9, 9.21.8
bind9 (Ubuntu package) - addressed in versions 1:9.20.0-2ubuntu3.2, 1:9.20.4-3ubuntu1.1
bind - update to 9.20.9-1
bind-utils-debuginfo - update to 9.20.9-150700.3.3.1
bind-debugsource - update to 9.20.9-150700.3.3.1
bind-utils - update to 9.20.9-150700.3.3.1
bind-debuginfo - update to 9.20.9-150700.3.3.1
bind - update to 9.20.9-150700.3.3.1
bind-doc - update to 9.20.9-150700.3.3.1

• Exploit #11411 - nhi-zero-trust-bypass (Demonstrates a real-world zero-trust bypass by exploiting BIND CVE-2025-40775 to disrupt DNS, break secret rotation, and expose static credentials in a cloud-native lab.) (May 23, 2025)

• https://kb.isc.org/docs/cve-2025-40775

• Remote denial of service in ISC BIND
• Arch Linux update for bind
• Ubuntu update for bind9
• SUSE update for bind