IBM SECURITY ADVISORY First Issued: Thu Jul 17 09:41:13 CDT 2025 The most recent version of this document is available here: https://aix.software.ibm.com/aix/efixes/security/libxml2_advisory9.asc Security Bulletin: Multiple vulnerabilities in libxml2 affect AIX =============================================================================== SUMMARY: Vulnerabilities in libxml2 could cause a denial of service or other possible undefined behavior (CVE-2025-49796, CVE-2025-49794, CVE-2025-49795, CVE-2025-6021). AIX uses libxml2 as part of its XML parsing functions. =============================================================================== VULNERABILITY DETAILS: CVEID: CVE-2025-49796 https://www.cve.org/CVERecord?id=CVE-2025-49796 DESCRIPTION: A vulnerability was found in libxml2. Processing certain sch:name elements from the input XML file can trigger a memory corruption issue. This flaw allows an attacker to craft a malicious XML input file that can lead libxml to crash, resulting in a denial of service or other possible undefined behavior due to sensitive data being corrupted in memory. CVSS Base Score: 9.1 CVSS Environmental Score*: Undefined CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H) CVEID: CVE-2025-49794 https://www.cve.org/CVERecord?id=CVE-2025-49794 DESCRIPTION: A use-after-free vulnerability was found in libxml2. This issue occurs when parsing XPath elements under certain circumstances when the XML schematron has the schema elements. This flaw allows a malicious actor to craft a malicious XML document used as input for libxml, resulting in the program's crash using libxml or other possible undefined behaviors. CVSS Base Score: 9.1 CVSS Environmental Score*: Undefined CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H) CVEID: CVE-2025-49795 https://www.cve.org/CVERecord?id=CVE-2025-49795 DESCRIPTION: A NULL pointer dereference vulnerability was found in libxml2 when processing XPath XML expressions. This flaw allows an attacker to craft a malicious XML input to libxml2, leading to a denial of service. 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-2025-6021 https://www.cve.org/CVERecord?id=CVE-2025-6021 DESCRIPTION: A flaw was found in libxml2's xmlBuildQName function, where integer overflows in buffer size calculations can lead to a stack-based buffer overflow. This issue can result in memory corruption or a denial of service when processing crafted input. 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) AFFECTED PRODUCTS AND VERSIONS: AIX 7.2, 7.3 VIOS 3.1, 4.1 The following fileset levels are vulnerable: key_fileset = aix Fileset Lower Level Upper Level KEY --------------------------------------------------------- bos.rte.control 7.2.5.0 7.2.5.205 key_w_fs bos.rte.control 7.3.1.0 7.3.1.3 key_w_fs bos.rte.control 7.3.2.0 7.3.2.3 key_w_fs bos.rte.control 7.3.3.0 7.3.3.1 key_w_fs 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 bos.rte.control REMEDIATION: A. APARS IBM has assigned the following APARs to this problem: AIX Level APAR Availability SP KEY ----------------------------------------------------- 7.2.5 IJ55266 ** SP11 key_w_apar 7.3.1 IJ55267 ** N/A key_w_apar 7.3.2 IJ55268 ** N/A key_w_apar 7.3.3 IJ55269 ** SP02 key_w_apar VIOS Level APAR Availability SP KEY ----------------------------------------------------- 3.1.4 IJ55266 ** N/A key_w_apar 4.1.0 IJ55268 ** N/A key_w_apar 4.1.1 IJ55269 ** 4.1.1.20 key_w_apar Subscribe to the APARs here: https://www.ibm.com/support/pages/apar/[apar number] By subscribing, you will receive periodic email alerting you to the status of the APAR, and a link to download the fix once it becomes available. B. FIXES IBM strongly recommends addressing the vulnerability now. AIX and VIOS fixes are available. The fixes are cumulative and address previously issued AIX/VIOS libxml2 security bulletins with respect to SP and TL. The AIX and VIOS fixes can be downloaded via https from: https://aix.software.ibm.com/aix/efixes/security/libxml2_fix9.tar The link above is 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. AIX Level Interim Fix (*.Z) KEY ---------------------------------------------- 7.2.5.8 IJ55266m9a.250716.epkg.Z key_w_fix 7.2.5.9 IJ55266m9a.250716.epkg.Z key_w_fix 7.2.5.10 IJ55266sAa.250716.epkg.Z key_w_fix 7.3.1.2 IJ55267m3a.250716.epkg.Z key_w_fix 7.3.1.3 IJ55267m3a.250716.epkg.Z key_w_fix 7.3.1.4 IJ55267m4a.250716.epkg.Z key_w_fix 7.3.2.2 IJ55268m3a.250716.epkg.Z key_w_fix 7.3.2.3 IJ55268m3a.250716.epkg.Z key_w_fix 7.3.2.4 IJ55268s4a.250716.epkg.Z key_w_fix 7.3.3.0 IJ55269m0a.250716.epkg.Z key_w_fix 7.3.3.1 IJ55269s1a.250716.epkg.Z key_w_fix Please note that the above table refers to AIX TL/SP level as opposed to fileset level, i.e., 7.3.2.3 is AIX 7300-02-03. Please reference the Affected Products and Version section above for help with checking installed fileset levels. VIOS Level Interim Fix (*.Z) KEY ----------------------------------------------- 3.1.4.41 IJ55266m9a.250716.epkg.Z key_w_fix 3.1.4.50 IJ55266m9a.250716.epkg.Z key_w_fix 3.1.4.60 IJ55266sAa.250716.epkg.Z key_w_fix 4.1.0.21 IJ55268m3a.250716.epkg.Z key_w_fix 4.1.0.30 IJ55268m3a.250716.epkg.Z key_w_fix 4.1.0.40 IJ55268s4a.250716.epkg.Z key_w_fix 4.1.1.0 IJ55269m0a.250716.epkg.Z key_w_fix 4.1.1.10 IJ55269s1a.250716.epkg.Z key_w_fix To extract the fixes from the tar file: tar xvf libxml2_fix9.tar cd libxml2_fix9 Verify you have retrieved the fixes intact: The checksums below were generated using the "openssl dgst -sha256 [filename]" command as the following: openssl dgst -sha256 filename KEY ----------------------------------------------------------------------------------------------------- 09072ee5de3ea2a158172cef4e588a3ff3a49ac3a9af47a4d6f95e1f5272d782 IJ55266m9a.250716.epkg.Z key_w_csum c1fd13c2fb68ff23bcf71f2e0122759364ff0569b25b67b234e05996c7c2f0a6 IJ55266sAa.250716.epkg.Z key_w_csum 3c109c71f157347b6ffa0388311c80ca33d80ec5726bfa452a7ae775639aef1a IJ55267m3a.250716.epkg.Z key_w_csum e2feda43d7a6944946e83d95f9ccc0d98856425396d68b9b425fbb0b3210dbd0 IJ55267m4a.250716.epkg.Z key_w_csum 4250419697629ef85008c70fa4931ece8ac6f6418dea76918c4bc915f7336987 IJ55268m3a.250716.epkg.Z key_w_csum 88f810415641825801b48091f05b92220b15b593576e37721a7ffbd5176b2d94 IJ55268s4a.250716.epkg.Z key_w_csum 3f89a207d93922f1bcc2014134d4c286560928d66da792a84748e9713602de17 IJ55269m0a.250716.epkg.Z key_w_csum 8e6dda03a2ffccdc34ab96ba28427cd99a863ae898daaf95bbf32a670f5dec6d IJ55269s1a.250716.epkg.Z key_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/libxml2_advisory9.asc.sig C. 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": 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/libxml2_advisory9.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 in libxml2 affect AIX https://www.ibm.com/support/pages/node/7239960 ACKNOWLEDGEMENTS: None. CHANGE HISTORY: First Issued: Thu Jul 17 09:41:13 CDT 2025 =============================================================================== *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.