IBM SECURITY ADVISORY First Issued: Wed Oct 21 00:15:44 CDT 2026 The most recent version of this document is available here: https://aix.software.ibm.com/aix/efixes/security/python_advisory22.asc Security Bulletin: Multiple vulnerabilities in Python affect AIX =============================================================================== SUMMARY: Vulnerabilities in Python: SSL/TLS Security Vulnerabilities (CVE-2026-19553, CVE-2026-19445), Archive Extraction / Tarfile Vulnerabilities (CVE-2026-19672, CVE-2026-82049, CVE-2026-87910), Authentication / Credential Exposure ( CVE-2026-15806), Memory Management Vulnerabilities (CVE-2026-15310, CVE-2026-102633, CVE-2026-77214), Unicode / Encoding Issues (CVE-2026-93990, CVE-2026-17084). Python is used by AIX as part of Ansible node management automation. =============================================================================== VULNERABILITY DETAILS: CVEID: CVE-2026-19553 https://www.cve.org/CVERecord?id=CVE-2026-19553 DESCRIPTION: ssl.SSLContext.wrap_bio() did not require the server_hostname argument to be non-None when SSLContext.check_hostname was enabled. Due to a missing parameter validation in SSLObject, hostname verification could be silently skipped, causing certificate validation to appear successful despite misconfiguration. CVSS Base Score: 7.6 CVSS Vector: (CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/ SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/ MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X) CVEID: CVE-2026-15310 https://www.cve.org/CVERecord?id=CVE-2026-15310 DESCRIPTION: When decompressing crafted ZIP files using bzip, LZMA, or Zstandard compression, Python could use an attacker-controlled size to pre-allocate memory, potentially leading to excessive memory consumption and denial of service through memory exhaustion. CVSS Base Score: 2.1 CVSS Vector: (CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/ SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/ MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X) CVEID: CVE-2026-19672 https://www.cve.org/CVERecord?id=CVE-2026-19672 DESCRIPTION: The tarfile module's extraction filters could create directories outside the intended destination when processing crafted member names containing path traversal sequences that leave and later return to the extraction path. This issue affects POSIX platforms only. CVSS Base Score: 6.3 CVSS Vector: (CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/ SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/ MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X) CVEID: CVE-2026-15806 https://www.cve.org/CVERecord?id=CVE-2026-15806 DESCRIPTION: The urllib.request HTTPPasswordMgr classes did not consider URL schemes when matching stored credentials. Credentials registered for HTTPS URLs could be sent to HTTP endpoints on the same host, allowing an attacker to capture sensitive authentication data in cleartext. CVSS Base Score: 6.0 CVSS Vector: (CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/ SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/ MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X) CVEID: CVE-2026-17084 https://www.cve.org/CVERecord?id=CVE-2026-17084 DESCRIPTION: The stringprep module incorrectly processed characters from RFC 3454 tables B.2 and B.3 by using newer Unicode attributes instead of the required Unicode 3.2.0 definitions. This could cause domain name mismatches when using IDNA 2003 processing. CVSS Base Score: 6.0 CVSS Vector: (CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/ SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/ MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X) CVEID: CVE-2026-102633 https://www.cve.org/CVERecord?id=CVE-2026-102633 DESCRIPTION: libexpat versions 2.7.2 through 2.8.5 contain an integer overflow vulnerability in the expat_realloc() function on 32-bit platforms. Malicious XML input can trigger heap buffer overflows, resulting in memory corruption or denial of service. CVSS Base Score: 5.9 CVSS Vector: (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H) CVEID: CVE-2026-93990 https://www.cve.org/CVERecord?id=CVE-2026-93990 DESCRIPTION: Expat before version 2.8.5 failed to verify that a UTF-16 high surrogate was followed by a valid low surrogate. Malformed UTF-16 XML input could be accepted, resulting in improper Unicode handling and data integrity issues. 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-2026-82049 https://www.cve.org/CVERecord?id=CVE-2026-82049 DESCRIPTION: In CPython 3.13 and earlier, the tarfile module's extraction filters were vulnerable to crafted archives containing a hard link to a symbolic link. Successful exploitation could expose files outside the extraction directory or modify their permissions and timestamps. CVSS Base Score: 8.4 CVSS Vector: (CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/ SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/ MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X) CVEID: CVE-2026-87910 https://www.cve.org/CVERecord?id=CVE-2026-87910 DESCRIPTION: When tarfile extracts a link on systems that do not support links, the filter function may be evaluated twice and one return value ignored. This could allow crafted archives to bypass intended filtering behavior and perform unauthorized file operations. CVSS Base Score: 5.7 CVSS Vector: (CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:N/VI:H/VA:N/SC:N/SI:N/ SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/ MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X) CVEID: CVE-2026-77214 https://www.cve.org/CVERecord?id=CVE-2026-77214 DESCRIPTION: libexpat contains a heap buffer over-read vulnerability in xmlparse.c. Repeated XML_ParseBuffer calls can advance an internal buffer pointer beyond the allocated memory region, allowing disclosure of adjacent heap memory and potentially bypassing ASLR protections. CVSS Base Score: 8.2 CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:L) CVEID: CVE-2026-19445 https://www.cve.org/CVERecord?id=CVE-2026-19445 DESCRIPTION: A remote unauthenticated TLS client can trigger a server crash or use-after-free condition when an sni_callback replaces SSLSocket.context and the original SSLContext is no longer referenced. This can result in execution through a freed pointer or denial of service. CVSS Base Score: 9.2 CVSS Vector: (CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/ SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/ MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X) AFFECTED PRODUCTS AND VERSIONS: AIX 7.3 VIOS 4.1 The vulnerabilities in the following filesets are being addressed: key_fileset = osrcaix Fileset Lower Level Upper Level KEY ------------------------------------------------------ python3.9.base 3.9.0.0 3.9.24.0 key_w_fs python3.11.base 3.11.0.0 3.11.16.0 key_w_fs python3.14.base 3.14.0.0 3.14.7.0 key_w_fs Note: A. Python 3.9 is out-of-support. Considering long term support, it is advised to upgrade to Python 3.11. B. Latest level of Python 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 the AIX user's guide. Example: lslpp -L | grep -i python3.11.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/python_fix22.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. AIX Level Fix (*.Z) KEY ----------------------------------------------- 7.3 python-3.11.17.0.tar.Z key_w_fix 7.3 python-3.14.8.0.tar.Z key_w_fix VIOS Level Fix (*.Z) KEY ----------------------------------------------- 4.1 python-3.11.17.0.tar.Z key_w_fix 4.1 python-3.14.8.0.tar.Z key_w_fix To extract the fixes from the tar file: tar xvf python_fix22.tar cd python_fix22.tar 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 --------------------------------------------------------------------------------------------------- c3d514db93863c4fd49f938e32a39cbe53da218a238ddd84a7856e5af9897eac python-3.11.17.0.tar.Z key_w_csum a8bfa9f1d58649881c0017ffa6c1c0880e821b363332734053b9e1d90e0577db python-3.14.8.0.tar.Z key_w_csum The checksums below were generated using the "openssl dgst -sha512 [filename]" command as the following: openssl dgst -sha512 filename KEY ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ c0d788bd5687edb763e93cbe7653531236ae01bae9292f2804244d85c9f9e3cc06273a59923def74eae2b5a5fe2201bd147fbc642b6bcb5f2aad82ddf807a50c python-3.11.17.0.tar.Z key_4K_w_csum 0816d177688554008792cf69ee7cdf3c838a6c9e5552dbaf9e29a7e231d94c30b5b3292f57f5bc3b04aaca86eaca18e27eb2d24cdb10cf0ad4f3b7389c3ce4fd python-3.14.8.0.tar.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/python_advisory22.asc.sig B. FIX AND INTERIM FIX INSTALLATION To extract the fixes from the tar file: zcat python-3.11.17.0.tar.Z | tar xvf - 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 . python3.11.base To install the fix package: installp -aXYd . python3.11.base 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/python_advisory22.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: 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 in Python affect AIX https://www.ibm.com/support/pages/node/7293240 ACKNOWLEDGEMENTS: None. CHANGE HISTORY: First Issued: Wed Oct 21 00:15:44 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.