IBM SECURITY ADVISORY First Issue: Mon Oct 12 00:46:10 CDT 2026 The most recent version of this document is available here: https://aix.software.ibm.com/aix/efixes/security/rpm_advisory5.asc Security Bulletin: Multiple vulnerabilities in rpm.rte affect AIX. =============================================================================== SUMMARY: Multiple Vulnerabilities in RPM could allow an attacker to cause denial of service (CVE-2026-41992, CVE-2026-56288, CVE-2026-18739), crash or remote code execution (CVE-2026-18743, CVE-2026-56289, CVE-2026-18839). RPM is used by AIX for package management. =============================================================================== VULNERABILITY DETAILS: CVEID: CVE-2026-41992 https://www.cve.org/CVERecord?id=CVE-2026-41992 DESCRIPTION: GNU gzip contains a global buffer overflow vulnerability in the LZH decompression logic caused by improper reuse of shared global state between different decompression formats within a single execution. GNU gzip maintains a global array shared across the LZ77, LZW, and LZH decompression routines and does not reinitialize it between files processed in the same invocation. By decompressing a specially crafted LZW file followed by a specially crafted LZH file in a single gzip -d command, an attacker can poison the shared state and trigger an out-of-bounds read in the LZH decoder, causing reads past the end of the allocated global buffer. 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-2026-56288 https://www.cve.org/CVERecord?id=CVE-2026-56288 DESCRIPTION: GNU patch is vulnerable to a NULL pointer dereference when processing a specially crafted unified-diff patch file. Improper handling of consecutive end-of-file newline markers can corrupt internal hunk data structures, causing the application to pass a NULL pointer to fwrite() during patch processing. An attacker can trigger this condition with a malicious patch file, causing the utility to crash and resulting in a denial of service. CVSS Base Score: 5.5 CVSS Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H) CVEID: CVE-2026-56289 https://www.cve.org/CVERecord?id=CVE-2026-56289 DESCRIPTION: GNU patch is vulnerable to a denial of service due to improper validation of hunk line offsets in unified-diff input. A specially crafted patch can specify an extremely large line number, causing the application to enter an effectively infinite processing loop while attempting to locate the requested position. This results in excessive CPU consumption and prevents the process from completing, causing the utility to become unresponsive and require manual termination. CVSS Base Score: 5.5 CVSS Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H) CVEID: CVE-2026-18743 https://www.cve.org/CVERecord?id=CVE-2026-18743 DESCRIPTION: A flaw was found in popt that allows an attacker to provide specially crafted configuration content which, when loaded, can lead to a small memory corruption issue. This occurs because of an error in how the poptConfigFileToString function reallocates memory for buffers. Successful exploitation could result in heap metadata corruption, potentially causing the affected process to become unavailable. CVSS Base Score: 2.5 CVSS Vector: (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L) CVEID: CVE-2026-18739 https://www.cve.org/CVERecord?id=CVE-2026-18739 DESCRIPTION: A flaw was found in popt, a command-line option parsing library. An off-by-one error in the poptStuffArgs function, when repeatedly called by a host application or through deep alias nesting, can lead to corruption of internal program data. This corruption could potentially enable a local attacker to execute arbitrary code if the host application unsafely processes the altered data. CVSS Base Score: 2.5 CVSS Vector: (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L) CVEID: CVE-2026-18839 https://www.cve.org/CVERecord?id=CVE-2026-18839 DESCRIPTION: An integer underflow was found in the popt library when formatting help text for option tables that exceed the terminal width. A local user who can cause an application to print help under those conditions may cause that application to crash or fail to display help, resulting in a denial of service of the affected application. CVSS Base Score: 2.2 CVSS Vector: (CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:L) AFFECTED PRODUCTS AND VERSIONS: AIX 7.2, 7.3 VIOS 4.1 The vulnerabilities in the following filesets are being addressed: key_fileset = aix Fileset Lower Level Upper Level KEY --------------------------------------------------------- rpm.rte 4.15.1.1000 4.15.1.1020 key_w_fs rpm.rte 4.15.1.2000 4.15.1.2016 key_w_fs rpm.rte 4.18.1.2000 4.18.1.2009 key_w_fs rpm.rte 4.20.1.2000 4.20.1.2002 key_w_fs Note: A. Latest level of RPM 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 rpm.rte REMEDIATION: 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/rpm_fix5.tar 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 rpm_fix5.tar For AIX 7.2: tar xvf rpm_fix5/rpm_41511021.tar For AIX 7.3 TL1: tar xvf rpm_fix5/rpm_41512017.tar For AIX 7.3 TL2 and TL3 and VIOS 4.1.0 and 4.1.1: tar xvf rpm_fix5/rpm_41812010.tar For AIX 7.3 TL4 and VIOS 4.1.2: tar xvf rpm_fix5/rpm_42012003.tar AIX Level Fix --------------------------------------- 7.2.5 rpm.rte.4.15.1.1021 7.3.1 rpm.rte.4.15.1.2017 7.3.2 rpm.rte.4.18.1.2010 7.3.3 rpm.rte.4.18.1.2010 7.3.4 rpm.rte.4.20.1.2003 VIOS Level Fix --------------------------------------- 4.1.0 rpm.rte.4.18.1.2010 4.1.1 rpm.rte.4.18.1.2010 4.1.2 rpm.rte.4.20.1.2003 IMPORTANT: If possible, it is recommended that a mksysb backup of the system be created. Verify it is both bootable and readable before proceeding. Note that all the previously reported security vulnerability fixes are also included in above mentioned fileset level. To preview the fix installation: installp -apYd . rpm To install the fix package: installp -aXYd . rpm Verify you have retrieved the fixes intact: The checksums below were generated using the following command: "openssl dgst -sha256 [file]" openssl dgst -sha256 filename KEY ------------------------------------------------------------------------------------------------- e4645b5fba55a22bc6a113671878a0ba5b4d74c77dd072d0f5e60f1e2c31260f rpm.rte.4.15.1.1021 key_w_csum b19519f49abdda456cfb4a4766522d93261117342e511a14d316a5d017bec18e rpm.rte.4.15.1.2017 key_w_csum a5ac1fc79dfd4371afb43194231357449c3079830a4962c1f9c7692ad4c7aa74 rpm.rte.4.18.1.2010 key_w_csum 61e201e9033ad84d5bd1241e71a814343b7718e2594d5943a39e66b71401eb43 rpm.rte.4.20.1.2003 key_w_csum The checksums below were generated using the following command: "openssl dgst -sha512 [file]" openssl dgst -sha512 filename KEY -------------------------------------------------------------------------------------------------------------------------------------------------------------------- 3b168b72b64b9af1037aad45cfc1ada853c1c8f89b3b9265f7378b3d9aa93df6a730a95d9b882709ec40003aac5608f95970e7d08f7606d487fef1d3ec081ef4 rpm.rte.4.15.1.1021 key_4K_w_csum 4320ae522b73d7d9f06494e082e1472806ffcd8d5a6e8dacaf3590ffc343ee52a8b7a5991df47c525cfbd1bef0add1dfa2c8ddb4114c32bc7d1ddfc2c64a3b18 rpm.rte.4.15.1.2017 key_4K_w_csum dcaa46b1508c0a4d9dc3ad30ff2e3c82f802ea27d89322dbbc552e0df9f5fd713ab3228fbb99c26e298c5211c8cb0ea9e69b70b9c2062dcc376b07e748edd0c0 rpm.rte.4.18.1.2010 key_4K_w_csum 0f6675fcb57afcd7f04f83a5b600b9b34767c92e715ef7a81a39688baf63f8195e429e76c1a6ff8b563dd92d5f28b3a408fbc81182344b94c6d9927c39c0f84c rpm.rte.4.20.1.2003 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/rpm_advisory5.asc.sig 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": http://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/rpm_advisory5.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/7292030 ACKNOWLEDGEMENTS: None. CHANGE HISTORY: First Issued: Mon Oct 12 00:46:10 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.