IBM SECURITY ADVISORY First Issued: Mon May 4 15:13:40 CDT 2026 The most recent version of this document is available here: https://aix.software.ibm.com/aix/efixes/security/openssl_advisory47.asc Security Bulletin: Multiple vulnerabilities impact AIX due to OpenSSL =============================================================================== SUMMARY: Vulnerabilities in OpenSSL could send contents of an uninitialized memory buffer (CVE-2026-31790), cause a use-after-free (CVE-2026-28387), cause a NULL pointer dereference (CVE-2026-28388, CVE-2026-28389, CVE-2026-28390), or lead to a buffer overflow (CVE-2026-31789). OpenSSL is used by AIX as part of AIX's secure network communications. =============================================================================== VULNERABILITY DETAILS: CVEID: CVE-2026-31790 https://www.cve.org/CVERecord?id=CVE-2026-31790 DESCRIPTION: Applications using RSASVE key encapsulation to establish a secret encryption key can send contents of an uninitialized memory buffer to a malicious peer. 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-2026-28387 https://www.cve.org/CVERecord?id=CVE-2026-28387 DESCRIPTION: An uncommon configuration of clients performing DANE TLSA-based server authentication, when paired with uncommon server DANE TLSA records, may result in a use-after-free and/or double-free on the client side. CVSS Base Score: 8.1 CVSS Vector: (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H) CVEID: CVE-2026-28388 https://www.cve.org/CVERecord?id=CVE-2026-28388 DESCRIPTION: When a delta CRL that contains a Delta CRL Indicator extension is processed a NULL pointer dereference might happen if the required CRL Number extension is missing. 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-2026-28389 https://www.cve.org/CVERecord?id=CVE-2026-28389 DESCRIPTION: During processing of a crafted CMS EnvelopedData message with KeyAgreeRecipientInfo a NULL pointer dereference can happen. 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-2026-28390 https://www.cve.org/CVERecord?id=CVE-2026-28390 DESCRIPTION: During processing of a crafted CMS EnvelopedData message with KeyTransportRecipientInfo a NULL pointer dereference can happen. 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-2026-31789 https://www.cve.org/CVERecord?id=CVE-2026-31789 DESCRIPTION: Converting an excessively large OCTET STRING value to a hexadecimal string leads to a heap buffer overflow on 32 bit platforms. CVSS Base Score: 9.8 CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H) AFFECTED PRODUCTS AND VERSIONS: AIX 7.2, 7.3 VIOS 4.1 The vulnerabilities in the following filesets are being addressed: key_fileset = osrcaix Fileset Lower Level Upper Level KEY ------------------------------------------------------ openssl.base 3.0.0.0 3.0.16.1000 key_w_fs Note: A. OpenSSL versions below 3.0 are out-of-support. Customers are advised to upgrade to OpenSSL 3.0. To find out whether the affected filesets are installed on your systems, refer to the lslpp command found in the AIX user's guide. Example: lslpp -L | grep -i openssl.base REMEDIATION: A. FIXES IBM strongly recommends addressing the vulnerability now. The fixes can be downloaded via https from: https://aix.software.ibm.com/aix/efixes/security/openssl_fix47.tar The links above are to a tar file containing this signed advisory, fix 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. Note that the tar file contains Interim fixes that are based on OpenSSL version, and AIX OpenSSL fixes are cumulative. If an OpenSSL fileset with VMRF higher than the affected level listed above is available from the web download site, then that fileset is the recommended remediation. You must be on the 'prereq for installation' level before applying the interim fix. This may require installing a new level(prereq version) first. Latest level of OpenSSL fileset is available from the web download site: https://www.ibm.com/resources/mrs/assets?source=aixbp&S_PKG=openssl AIX Level Interim Fix (*.Z) Fileset Name(prereq for installation) KEY --------------------------------------------------------------------------------------- 7.2, 7.3 301610mc.260424.epkg.Z openssl.base(3.0.16.1000) key_w_fix VIOS Level Interim Fix (*.Z) Fileset Name(prereq for installation) KEY --------------------------------------------------------------------------------------- 4.1 301610mc.260424.epkg.Z openssl.base(3.0.16.1000) key_w_fix To extract the fixes from the tar file: tar xvf openssl_fix47.tar cd openssl_fix47 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 ----------------------------------------------------------------------------------------------------- e43474e2e5aa096a19b36345c1e62c9df6ff0425820505a8eb9e751036ad0d55 301610mc.260424.epkg.Z key_w_csum The checksums below were generated using the "openssl dgst -sha512 [filename]" command as the following: openssl dgst -sha512 filename ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ 319b1ae371438a00ddedcd5b7969e869cb46c646c888abf5906cb43232e2b622f3b869ff8972a2be8eafdf90c1347be83eca35115f1efe82cb8ed0d33843921e 301610mc.260424.epkg.Z 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 AIX Support at https://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/openssl_advisory47.asc.sig B. FIX AND INTERIM FIX INSTALLATION 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/openssl_advisory47.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: Review this information as needed, no action required. Complete CVSS v3 Guide: https://www.first.org/cvss/user-guide On-line Calculator v3: https://www.first.org/cvss/calculator/3.0 RELATED INFORMATION: Security Bulletin: Multiple vulnerabilities impact AIX due to OpenSSL https://www.ibm.com/support/pages/node/7271681 ACKNOWLEDGEMENTS: None. CHANGE HISTORY: First Issued: Mon May 4 15:13:40 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.