IBM SECURITY ADVISORY First Issued: Thu Feb 5 15:13:54 CST 2026 The most recent version of this document is available here: https://aix.software.ibm.com/aix/efixes/security/perl_advisory12.asc Security Bulletin: AIX is vulnerable to denial of service and possible code execution due to Perl (WS-2025-0004) =============================================================================== SUMMARY: Vulnerability in Perl could allow an attacker to cause a denial of service or possibly execute code (WS-2025-0004). AIX uses Perl in various operating system components. =============================================================================== VULNERABILITY DETAILS: CVEID: WS-2025-0004 https://www.mend.io/vulnerability-database/WS-2025-0004 DESCRIPTION: Fix a class of false positives where input should have been rejected with error XML_ERROR_ASYNC_ENTITY; regression from CVE-2024-8176 fix pull request #973 (of Expat 2.7.0 and related backports). 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 7.3 VIOS 4.1 The vulnerability is being addressed in the following fileset levels: key_fileset = aix Fileset Lower Level Upper Level KEY --------------------------------------------------------- perl.rte 5.34.0.0 5.34.1.8 key_w_fs perl.rte 5.38.0.0 5.38.2.3 key_w_fs Note: A. Latest level of Perl 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 perl.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/perl_fix12.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 perl_fix12.tar For AIX 7.3 TL2 and VIOS 4.1.0: tar xvf perl_fix12/perl_53419.tar For AIX 7.3 TL3, TL4 and VIOS 4.1.1, 4.1.2: tar xvf perl_fix12/perl_53824.tar AIX Level Fix -------------------------------------- 7.3.2 perl.rte.5.34.1.9 7.3.3, 7.3.4 perl.rte.5.38.2.4 VIOS Level Fix -------------------------------------- 4.1.0 perl.rte.5.34.1.9 4.1.1, 4.1.2 perl.rte.5.38.2.4 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 . perl To install the fix package: installp -aXYd . perl 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 ----------------------------------------------------------------------------------------------- 78c38fb873fd4a43d595cbcf2bb30dcfc1ec80070656df4309b07fe21b7c90b0 perl.rte.5.34.1.9 key_w_csum f65103d594700b81e1c13d220d3cc3d2dcc22421dc55cdf7859c5a1e27b18408 perl.rte.5.38.2.4 key_w_csum openssl dgst -sha512 filename ------------------------------------------------------------------------------------------------------------------------------------------------------------------ 91525a46b05553a8af13e6822ab29bdf48e2467431aa1fe0ddc1d67508af07fb5aa56e9667603f87169f929a72b910c0d1005984822e085c789f84b27c9196f4 perl.rte.5.34.1.9 key_4K_w_csum a80a52cf48b6171fb97c0873d1564b792f5589d9355f976262b261ecf56e1a0ea25f9e180941e37bee7575ab30dc1538405ffa95370660360c61a9c49b6eb283 perl.rte.5.38.2.4 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/perl_advisory12.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 the fileset installation: installp -apYd . perl To install the fileset update: installp -aXYd . perl 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/perl_advisory12.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: AIX is vulnerable to denial of service and possible code execution due to Perl (WS-2025-0004) https://www.ibm.com/support/pages/node/7259886 ACKNOWLEDGEMENTS: None. CHANGE HISTORY: First Issued: Thu Feb 5 15:13:54 CST 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.