IBM SECURITY ADVISORY First Issued: Wed Sep 16 01:36:11 CDT 2026 The most recent version of this document is available here: https://aix.software.ibm.com/aix/efixes/security/bind_advisory31.asc Security Bulletin: Multiple vulnerabilities impact AIX due to ISC BIND (CVE-2026-10723, CVE-2026-10822, CVE-2026-11331, CVE-2026-11622, CVE-2026-11721, CVE-2026-12617, CVE-2026-13204, CVE-2026-13321) =============================================================================== SUMMARY: Vulnerabilities in ISC BIND could cause: Allowing forged authenticated NXDOMAIN responses (CVE-2026-10723), Denial of service (CVE-2026-10822, CVE-2026-11331, CVE-2026-11622, CVE-2026-12617, CVE-2026-13204), DNS cache poisoning (CVE-2026-11721, CVE-2026-13321). AIX uses ISC BIND as as part of its DNS functions. =============================================================================== VULNERABILITY DETAILS: CVEID: CVE-2026-10723 https://www.cve.org/CVERecord?id=CVE-2026-10723 DESCRIPTION: BIND may accept incorrect child-zone NSEC3 records as valid, which could allow an attacker to forge authenticated NXDOMAIN responses. This issue affects BIND 9 versions 9.18.0 through 9.18.50, 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1. CVSS Base Score: 6.8 CVSS Vector: (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N) CVEID: CVE-2026-10822 https://www.cve.org/CVERecord?id=CVE-2026-10822 DESCRIPTION: If BIND encounters a particular invalid data structure in a DNS record, it will accept the invalid data and may subsequently abort and exit. A malformed PRIVATEDNS algorithm identifier can be stored and later trigger a consistency check failure when rendered to text. This issue affects BIND 9 versions 9.18.0 through 9.18.50, 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, 9.18.11-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1. CVSS Base Score: 6.5 CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H) CVEID: CVE-2026-11331 https://www.cve.org/CVERecord?id=CVE-2026-11331 DESCRIPTION: 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 during RPZ processing. This may bypass the RPZ rule and can also cause BIND 9 to exit unexpectedly. This issue affects BIND 9 versions 9.16.0 through 9.18.50, 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, 9.16.8-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1. CVSS Base Score: 7.5 CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N) CVEID: CVE-2026-11622 https://www.cve.org/CVERecord?id=CVE-2026-11622 DESCRIPTION: A DNSSEC validating resolver under a random subdomain attack against a DNSSEC-signed zone can suffer from runaway memory usage. An attacker able to send queries faster than validation can occur may cause memory consumption far beyond the configured max-cache-size limit. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1. CVSS Base Score: 7.5 CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) CVEID: CVE-2026-11721 https://www.cve.org/CVERecord?id=CVE-2026-11721 DESCRIPTION: An attacker's zone can respond with an RRSIG containing fewer labels than the zone in which it is stored. This may cause named to generate a wildcard name shorter than the attacker's zone, potentially resulting in cache poisoning when synth-from-dnssec is enabled. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1. CVSS Base Score: 7.5 CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N) CVEID: CVE-2026-12617 https://www.cve.org/CVERecord?id=CVE-2026-12617 DESCRIPTION: Unexpected program termination may occur based on the ordering or content of responses to CNAME, DNAME, and A record queries. Under specific response sequences, named may quit unexpectedly due to a reachable assertion. This issue affects BIND 9 versions 9.18.0 through 9.18.50, 9.20.0 through 9.20.24, 9.18.11-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1. CVSS Base Score: 7.5 CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) CVEID: CVE-2026-13204 https://www.cve.org/CVERecord?id=CVE-2026-13204 DESCRIPTION: If a provably insecure domain is covered by both an NSEC and NSEC3 record at the parent and only one record type has a corresponding RRSIG, BIND may exit unexpectedly with an assertion while validating the proof. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1. CVSS Base Score: 7.5 CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) CVEID: CVE-2026-13321 https://www.cve.org/CVERecord?id=CVE-2026-13321 DESCRIPTION: The BIND resolver accepts validly signed NSEC records where the Next Domain Name field points outside the signer's zone. This validation weakness may allow malicious responses to be accepted. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1. CVSS Base Score: 8.6 CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N) AFFECTED PRODUCTS AND VERSIONS: AIX 7.2, 7.3 VIOS 4.1 The vulnerabilities are being addressed for the following filesets: key_fileset = aix Fileset Lower Level Upper Level KEY ---------------------------------------------------------- bind.rte 7.1.916.0 7.1.916.4800 key_w_fs bind.rte 7.2.916.0 7.2.916.4801 key_w_fs bind.rte 7.2.918.0 7.2.918.4900 key_w_fs bind.rte 7.3.916.0 7.3.916.4800 key_w_fs bind.rte 7.3.918.0 7.3.918.4900 key_w_fs Note: A. Latest level of BIND fileset is available from the web download site: https://www.ibm.com/resources/mrs/assets?source=aixbp To find out whether the affected filesets are installed on your systems, refer to the lslpp command found in AIX user's guide. Example: lslpp -L | grep -i bind.rte REMEDIATION: A. FIXES IBM strongly recommends addressing the vulnerability now. The AIX and VIOS fixes can be downloaded via https from: https://aix.software.ibm.com/aix/efixes/security/bind_fix31.tar The fileset update has a dependency on OpenSSL 3.0. OpenSSL 3.0 may be downloaded from: https://www.ibm.com/resources/mrs/assets?source=aixbp The link above is to a tar file containing this signed advisory, install packages, and OpenSSL signatures for each package. The fixes below include prerequisite checking. This will enforce the correct mapping between the fixes and AIX Technology Levels. To extract the fixes from the tar file: tar xvf bind_fix31.tar For AIX 7.2 (requires OpenSSL 3.0): tar xvf bind_fix31/72bind920.tar For AIX 7.3 and VIOS 4.1: tar xvf bind_fix31/73bind920.tar IMPORTANT: If possible, it is recommended that a mksysb backup of the system be created. Verify it is both bootable and readable before proceeding. To preview the fix installation: installp -apYd . bind To install the fix package: installp -aXYd . bind Verify you have retrieved the fixes intact: The checksums below were generated using the "openssl dgst -sha256 [file]" command as the following: openssl dgst -sha256 filename KEY --------------------------------------------------------------------------------------- 020823947e7972c028dc946d91c5ec1db29f359b14168a30685b2b000cc2e4e1 72bind.rte key_w_csum 274e3da930593a7c3c209b65eb31fb35092f29c2c29e6db6d84fc5f1d58170db 73bind.rte key_w_csum openssl dgst -sha512 filename KEY ---------------------------------------------------------------------------------------------------------------------------------------------------------- cfdc8b558a5da6a7d1e6c9fa010e41e132f4bf54cdfbc6590dcacd84e56a87650aa4b99dde40fba154737ef8fe7940383675274b0cdf7cdab254c4aba1b476cf 72bind.rte key_4K_w_csum de4630037befa218258c36fee9cad4245d5ed0a2d7cf8a17d7e5b8bbfacb1e45daae808e3dc9cdd41e358e2106819163aa5c2ccbf876f330da2c451baa847c05 73bind.rte key_4K_w_csum These sums should match exactly. The OpenSSL signatures in the tar file and on this advisory can also be used to verify the integrity of the fixes. If the sums or signatures cannot be confirmed, contact IBM Support at http://ibm.com/support/ and describe the discrepancy. openssl dgst -sha256 -verify [pubkey_file] -signature [advisory_file].sig [advisory_file] openssl dgst -sha256 -verify [pubkey_file] -signature [ifix_file].sig [ifix_file] Published advisory OpenSSL signature file location: https://aix.software.ibm.com/aix/efixes/security/bind_advisory31.asc.sig B. FIX AND INTERIM FIX INSTALLATION If possible, it is recommended that a mksysb backup of the system be created. Verify it is both bootable and readable before proceeding. To preview a fix installation: installp -a -d fix_name -p all # where fix_name is the name of the # fix package being previewed. To install a fix package: installp -a -d fix_name -X all # where fix_name is the name of the # fix package being installed. Interim fixes have had limited functional and regression testing but not the full regression testing that takes place for Service Packs; however, IBM does fully support them. Interim fix management documentation can be found at: https://www.ibm.com/support/pages/managing-interim-fixes-aix To preview an interim fix installation: emgr -e ipkg_name -p # where ipkg_name is the name of the # interim fix package being previewed. To install an interim fix package: emgr -e ipkg_name -X # where ipkg_name is the name of the # interim fix package being installed. WORKAROUNDS AND MITIGATIONS: None. =============================================================================== CONTACT US: Note: Keywords labeled as KEY in this document are used for parsing purposes. If you would like to receive AIX Security Advisories via email, please visit "My Notifications": https://www.ibm.com/support/mynotifications Contact IBM Support for questions related to this announcement: https://ibm.com/support/ For information on how to securely verify AIX security bulletins and fixes: https://www.ibm.com/support/pages/node/6985269 To obtain the OpenSSL public key that can be used to verify the signed advisories and ifixes: Download the key from our web page: https://aix.software.ibm.com/aix/efixes/security/systems_p_os_aix_security_pubkey.txt To verify the AIX/VIOS security bulletin: Published advisory OpenSSL signature file location: https://aix.software.ibm.com/aix/efixes/security/bind_advisory31.asc.sig openssl dgst -sha256 -verify [pubkey_file] -signature [advisory_file].sig [advisory_file] Please contact your local IBM AIX support center for any assistance. REFERENCES: Complete CVSS v3 Guide: http://www.first.org/cvss/user-guide On-line Calculator v3: http://www.first.org/cvss/calculator/3.0 RELATED INFORMATION: IBM Secure Engineering Web Portal http://www.ibm.com/security/secure-engineering/bulletins.html IBM Product Security Incident Response Blog https://www.ibm.com/blogs/psirt/ Security Bulletin: https://www.ibm.com/support/pages/node/7287477 ACKNOWLEDGEMENTS: None. CHANGE HISTORY: Supported fileset level is updated. First Issued: Wed Sep 16 01:36:11 CDT 2026 =============================================================================== *The CVSS Environment Score is customer environment specific and will ultimately impact the Overall CVSS Score. Customers can evaluate the impact of this vulnerability in their environments by accessing the links in the Reference section of this Security Bulletin. Disclaimer According to the Forum of Incident Response and Security Teams (FIRST), the Common Vulnerability Scoring System (CVSS) is an "industry open standard designed to convey vulnerability severity and help to determine urgency and priority of response." IBM PROVIDES THE CVSS SCORES "AS IS" WITHOUT WARRANTY OF ANY KIND, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. CUSTOMERS ARE RESPONSIBLE FOR ASSESSING THE IMPACT OF ANY ACTUAL OR POTENTIAL SECURITY VULNERABILITY.