IBM SECURITY ADVISORY First Issued: Mon Jun 29 06:22:46 CDT 2026 The most recent version of this document is available here: https://aix.software.ibm.com/aix/efixes/security/bind_advisory30.asc Security Bulletin: Multiple vulnerabilities impact AIX due to ISC BIND (CVE-2025-13878, CVE-2026-1519, CVE-2026-3592, CVE-2026-5946, CVE-2026-5950) =============================================================================== SUMMARY: Vulnerabilities in ISC BIND could cause: CVE-2025-13878: Excessive resource consumption or service interruption. CVE-2026-1519: Excessive resources consumption or terminate unexpectedly. CVE-2026-3592: DNS amplification attacks. CVE-2026-5946: Unexpected behavior, potentially crashing the server. CVE-2026-5950: High CPU utilization and resource exhaustion resulting in a denial of service. AIX uses ISC BIND as as part of its DNS functions. =============================================================================== VULNERABILITY DETAILS: CVEID: CVE-2025-13878 https://www.cve.org/CVERecord?id=CVE-2025-13878 DESCRIPTION: Malformed BRID/HHIT records can cause `named` to terminate unexpectedly. This issue affects BIND 9 versions 9.18.40 through 9.18.43, 9.20.13 through 9.20.17, 9.21.12 through 9.21.16, 9.18.40-S1 through 9.18.43-S1, and 9.20.13-S1 through 9.20.17-S1. CVSS Base score: 7.5 CVSS Environmental Score*: Undefined CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) CVEID: CVE-2026-1519 https://www.cve.org/CVERecord?id=CVE-2026-1519 DESCRIPTION: If a BIND resolver is performing DNSSEC validation and encounters a maliciously crafted zone, the resolver may consume excessive CPU. Authoritative-only servers are generally unaffected, although there are circumstances where authoritative servers may make recursive queries (see: https://kb.isc.org/docs/why-does-my-authoritative-server-make-recursive-queries). This issue affects BIND 9 versions 9.11.0 through 9.16.50, 9.18.0 through 9.18.46, 9.20.0 through 9.20.20, 9.21.0 through 9.21.19, 9.11.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.46-S1, and 9.20.9-S1 through 9.20.20-S1. CVSS Base score: 7.5 CVSS Environmental Score*: Undefined CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) CVEID: CVE-2026-3592 https://www.cve.org/CVERecord?id=CVE-2026-3592 DESCRIPTION: BIND resolvers are vulnerable to an amplified resource consumption/exhaustion attack. If a victim resolver makes a query to a specially crafted zone, the resolver will consume disproportionate resources. 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. CVSS Base score: 5.3 CVSS Environmental Score*: Undefined CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L) CVEID: CVE-2026-5946 https://www.cve.org/CVERecord?id=CVE-2026-5946 DESCRIPTION: 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. CVSS Base score: 7.5 CVSS Environmental Score*: Undefined CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) CVEID: CVE-2026-5950 https://www.cve.org/CVERecord?id=CVE-2026-5950 DESCRIPTION: An unbounded resend loop vulnerability exists in the BIND 9 resolver state machine during bad-server handling, enabling a remote unauthenticated attacker to cause severe resource exhaustion by sending queries that trigger specific retry conditions. This issue affects BIND 9 versions 9.18.36 through 9.18.48, 9.20.8 through 9.20.22, 9.21.7 through 9.21.21, 9.18.36-S1 through 9.18.48-S1, and 9.20.9-S1 through 9.20.22-S1. CVSS Base score: 5.3 CVSS Environmental Score*: Undefined CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L) AFFECTED PRODUCTS AND VERSIONS: AIX 7.2, 7.3 VIOS 4.1 The vulnerabilities are being addressed in 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 7.2.918.2802 key_w_fs bind.rte 7.3.916.0 7.3.916.4800 key_w_fs bind.rte 7.3.918.0 7.3.918.2802 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_fix30.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_fix30.tar For AIX 7.2 (requires OpenSSL 3.0): tar xvf bind_fix30/72bind918.tar For AIX 7.3 and VIOS 4.1: tar xvf bind_fix30/73bind918.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 --------------------------------------------------------------------------------------- 4981af0a108a6d3d2ad9fac7738ffe05c00b3e045d9b90e3b2280bd3df088946 72bind.rte key_w_csum 4e8ae1957564c90e495cad785fe42a1223ddb4186f120db07770fde68f455e9c 73bind.rte key_w_csum openssl dgst -sha512 filename ---------------------------------------------------------------------------------------------------------------------------------------------------------- 379fed277de0f554de1a0caf72781296a6b848e1e8d7775577071054f070362c2371d27b8e114f539f0b176ce6a540789b0cc7b13f72a62a87d3076ae7a7e8f3 72bind.rte key_4K_w_csum 46d6266cdae6fb44d86bf14578be1f6fc61409389d1dac211330e52c2043e70e44983179b440dad3bd2bbf53b5a3a925f3a5efd58dbe62e2488bc8bd22d28dc2 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_advisory30.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_advisory29.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: Multiple vulnerabilities impact AIX due to ISC BIND (CVE-2025-40778, CVE-2025-40780, CVE-2025-8677) https://www.ibm.com/support/pages/node/7261171 ACKNOWLEDGEMENTS: None. CHANGE HISTORY: First Issued: Mon Jun 29 06:22:46 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.