CVE-2026-5946: Invalid handling of CLASS != IN
Invalid handling of CLASS != IN
Other sources
Multiple flaws have been identified in named related to the handling of DNS messages whose CLASS is not Internet (IN) — for example, CHAOS or HESIOD, or DNS messages that specify meta-classes (ANY or NONE) in the question section. Specially crafted requests reaching the affected code paths — recursion, dynamic updates (UPDATE), zone change notifications (NOTIFY), or processing of IN-specific record types in non-IN data — can cause assertion failures in named. This issue affects BIND 9 versions 9.11.0 through 9.16.50, 9.18.0 through 9.18.48, 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, 9.11.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.48-S1, and 9.20.9-S1 through 9.20.22-S1.
— MITRE
Multiple flaws have been identified in named related to the handling of DNS messages whose CLASS is not Internet (IN) — for example, CHAOS or HESIOD, or DNS messages that specify meta-classes (ANY or NONE) in the question section. Specially crafted requests reaching the affected code paths — recursion, dynamic updates (UPDATE), zone change notifications (NOTIFY), or processing of IN-specific record types in non-IN data — can cause assertion failures in named.
— Red Hat
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
debian/bind9to a version that resolves this vulnerability.Fixed in 1:9.18.49-1~deb12u1Fixed in 1:9.20.23-1~deb13u1Fixed in 1:9.20.23-1 - Upgrade
Upgrade
ISC BIND 9 namedto a version that resolves this vulnerability.Fixed in 9.18.49 - Upgrade
Upgrade
ISC BIND 9 namedto a version that resolves this vulnerability.Fixed in 9.20.23 - Upgrade
Upgrade
ISC BIND 9 namedto a version that resolves this vulnerability.Fixed in 9.21.22 - Upgrade
Upgrade
ISC BIND 9 namedto a version that resolves this vulnerability.Fixed in 9.18.49-S1 - Upgrade
Upgrade
ISC BIND 9 namedto a version that resolves this vulnerability.Fixed in 9.20.23-S1
Event History
Frequently Asked Questions
What is the severity of CVE-2026-5946?
CVE-2026-5946 is rated as a high severity vulnerability due to the potential for abuse in handling DNS messages.
How do I fix CVE-2026-5946?
To address CVE-2026-5946, it is recommended to upgrade to the latest version of ISC BIND 9 that is not affected by this vulnerability.
Which versions of ISC BIND 9 are affected by CVE-2026-5946?
CVE-2026-5946 affects ISC BIND 9 versions from 9.11.0 to 9.16.50, 9.18.0 to 9.18.48, 9.20.0 to 9.20.22, and 9.21.0 to 9.21.21.
What types of DNS messages are involved in CVE-2026-5946?
CVE-2026-5946 involves DNS messages whose CLASS is not 'IN', such as 'CHAOS' or 'HESIOD', and those that specify meta-classes like 'ANY' or 'NONE'.
Can CVE-2026-5946 cause a denial of service?
Yes, CVE-2026-5946 can lead to denial of service under certain conditions due to the way DNS messages are processed.