CVE-2026-11331: Potential wildcard CNAME RPZ policy bypass
An attacker who knows (or guesses) that a resolver uses RPZ with wildcard CNAME policies can craft query names long enough to trigger a NAMETOOLONG error condition during RPZ processing. This is not handled correctly and may lead to defeating the RPZ rule. It also may lead to an unexpected exit of the BIND 9 software.
Other sources
Potential wildcard CNAME RPZ policy bypass
— Microsoft
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 9.20.26-1 - Upgrade
Upgrade
debian/bind9to a version that resolves this vulnerability.Fixed in 1:9.16.50-1~deb11u6Fixed in 1:9.18.49-1~deb12u2Fixed in 1:9.20.26-1~deb13u1Fixed in 1:9.20.26-1Fixed in 1:9.20.27-1 - Upgrade
Upgrade
ISC BIND 9to a version that resolves this vulnerability.Fixed in 9.20.26 - Upgrade
Upgrade
ISC BIND 9to a version that resolves this vulnerability.Fixed in 9.21.24 - Upgrade
Upgrade
ISC BIND 9to a version that resolves this vulnerability.Fixed in 9.20.26-S1
Event History
Frequently Asked Questions
What is the severity of CVE-2026-11331?
CVE-2026-11331 has a high severity score of 7.5.
How can I mitigate the risks associated with CVE-2026-11331?
To mitigate CVE-2026-11331, update to the latest version of BIND 9 that addresses this vulnerability.
What types of systems are affected by CVE-2026-11331?
CVE-2026-11331 affects systems using Internet Systems Consortium BIND 9 with wildcard CNAME RPZ policies.
What kind of attack does CVE-2026-11331 enable?
CVE-2026-11331 enables an attacker to bypass RPZ rules by triggering a NAMETOOLONG error condition.
Is there any exploit available for CVE-2026-11331?
While the details of exploited conditions are not specified, the vulnerability allows crafted queries to bypass security policies.