CVE-2025-40777

Publication date 16 July 2025

Last updated 23 July 2025

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

7.5 · High

Score breakdown

Description

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.

Read the notes from the security team

Status

Package Ubuntu Release Status
bind9 25.04 plucky
Fixed 1:9.20.4-3ubuntu1.2
24.04 LTS noble
Not affected
22.04 LTS jammy
Not affected
20.04 LTS focal
Not affected
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty
Not affected
isc-dhcp 25.04 plucky
Not affected
24.04 LTS noble
Not affected
22.04 LTS jammy
Not affected
20.04 LTS focal
Not affected
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty
Not affected
bind9-libs 25.04 plucky Not in release
24.04 LTS noble Not in release
22.04 LTS jammy
Not affected
20.04 LTS focal
Not affected

Notes

alexmurray

As of isc-dhcp-4.4.3-1, isc-dhcp vendors bind9 libs

mdeslaur

in focal and jammy, isc-dhcp uses the bind9-libs package only affects 9.20.x and 9.21.x

Severity score breakdown

Parameter Value
Base score 7.5 · High
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Scope Unchanged
Confidentiality None
Integrity impact None
Availability impact High
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

Related Ubuntu Security Notices (USN)

Other references