IBM SECURITY ADVISORY First Issued: Mon Sep 28 00:55:59 CDT 2026 The most recent version of this document is available here: https://aix.software.ibm.com/aix/efixes/security/perl_advisory14.asc Security Bulletin: Multiple perl vulnerabilities impact AIX. =============================================================================== SUMMARY: Vulnerabilities in Perl could cause Information Disclosure(CVE-2026-57432), Heap Buffer Overflow(CVE-2026-8376), Regex Validation Bypass(CVE-2026-13221), Host Validation Bypass(CVE-2026-19953), Out-of-Bounds Read/Write (CVE-2026-15534), Access Control Bypass(CVE-2026-19487). =============================================================================== VULNERABILITY DETAILS: CVEID: CVE-2026-57432 https://www.cve.org/CVERecord?id=CVE-2026-57432 DESCRIPTION: Perl versions before 5.40.5-RC1, from 5.41.0 before 5.42.3-RC1, and from 5.43.0 before 5.43.11 have an integer overflow in S_measure_struct leading to an out-of-bounds heap read in pack and unpack operations. CVSS Base Score: 8.4 CVSS Vector:(CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H) CVEID: CVE-2026-8376 https://www.cve.org/CVERecord?id=CVE-2026-8376 DESCRIPTION: Perl versions before 5.40.5-RC1, from 5.41.0 before 5.42.3-RC1, and from 5.43.0 before 5.43.11 have a heap buffer overflow during compilation of specially crafted regular expressions on 32-bit builds. 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) CVEID: CVE-2026-13221 https://www.cve.org/CVERecord?id=CVE-2026-13221 DESCRIPTION: Perl versions before 5.40.5-RC1, from 5.41.0 before 5.42.3-RC1, and from 5.43.0 before 5.43.10 can produce incorrect regular expression matches due to an integer overflow in trie optimization logic. CVSS Base Score: 9.1 CVSS Vector:(CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H) CVEID: CVE-2026-19953 https://www.cve.org/CVERecord?id=CVE-2026-19953 DESCRIPTION: URI versions before 5.36 for Perl incorrectly encode non-NFC host names, which can cause inconsistencies between hostname validation and actual network resolution, potentially bypassing security checks. CVSS Base Score: 6.5 CVSS Vector:(CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N) CVEID: CVE-2026-15534 https://www.cve.org/CVERecord?id=CVE-2026-15534 DESCRIPTION: Perl versions through 5.45.1 contain out-of-bounds heap reads and writes during regular expression matching due to an undersized superlinear cache allocation. CVSS Base Score: 5.7 CVSS Vector:(CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H) CVEID: CVE-2026-19487 https://www.cve.org/CVERecord?id=CVE-2026-19487 DESCRIPTION: Perl versions from 5.9.4 before 5.41.9 may return incorrect regular expression match results because of a stale failure flag in the Aho-Corasick prescan logic, potentially affecting security decisions. CVSS Base Score: 5.3 CVSS Vector:(CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L) Note: CVE-2026-8376, CVE-2026-13221 are impacting only fileset levels 5.38.x.x. 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 --------------------------------------------------------- perl.rte 5.28.0.0 5.28.1.12 key_w_fs perl.rte 5.34.0.0 5.34.1.11 key_w_fs perl.rte 5.38.0.0 5.38.2.6 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_fix14.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_fix14.tar For AIX 7.2 TL5: tar xvf perl_fix14/perl_528113 For AIX 7.3 TL2: tar xvf perl_fix14/perl_534112 For AIX 7.3 TL3, TL4 and VIOS 4.1: tar xvf perl_fix14/perl_53827 AIX Level Fix -------------------------------------- 7.2.5 perl.rte.5.28.1.13 7.3.2 perl.rte.5.34.1.12 7.3.3 perl.rte.5.38.2.7 7.3.4 perl.rte.5.38.2.7 VIOS Level Fix -------------------------------------- 4.1.0 perl.rte.5.34.1.12 4.1.1 perl.rte.5.38.2.7 4.1.2 perl.rte.5.38.2.7 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 ----------------------------------------------------------------------------------------------- b7703c60190d50e458a991050a69701cfd60a39fecd0ff5c21c26cceee04c36a perl.rte.5.28.1.13 key_w_csum 95880cbce79938c63322a62a662965b705dca1ca1408d7166f5de9146228e596 perl.rte.5.34.1.12 key_w_csum 9a8d67573b82c14ecb310ce96c956dd90a1e1e2f57a069c8abe7807bd3620aa3 perl.rte.5.38.2.7 key_w_csum The checksums below were generated using the "openssl dgst -sha512 [file]" command as the following: openssl dgst -sha512 filename KEY ------------------------------------------------------------------------------------------------------------------------------------------------------------------ ae8588c8af2ebfc96446e148b133c46acb8ee2f0eee6a088b14129537ce02c14f9d51769ddf053274658fa5f0c8cfef3b1f8e9fb10ea69a2b6c40c852c352adc perl.rte.5.28.1.13 key_4K_w_csum 6d3638c031c66f41831ef997578f9a01b0ddd6eddbc5e34f180a184561c226453e1adc37defb5411d930b96b736465f5cf7c8423c6281448fcb825d6d0b5c142 perl.rte.5.34.1.12 key_4K_w_csum bb19fd4189ab861069f77047270bf77018d1450b208945d4d970d2d8d1a3c251737678523baa8638d1130124660b39e2c82d6ae4ad819a68a814bae5de5615f7 perl.rte.5.38.2.7 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_advisory14.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_advisory14.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 perl vulnerabilities impact AIX. https://www.ibm.com/support/pages/node/7289720 ACKNOWLEDGEMENTS: None. CHANGE HISTORY: First Issued: Mon Sep 28 00:55:59 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.