ESB-2026.4851

=========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2026.4851 IBM MQ Appliance is affected by mulitple open source vulnerabilities (CVE-2026-23193, CVE-2026-23231, CVE-2026-3497) 8 May 2026 =========================================================================== AUSCERT Security Bulletin Summary --------------------------------- Product: IBM MQ Appliance Publisher: IBM Operating System: Appliance Resolution: Patch/Upgrade CVE Names: CVE-2026-23193 CVE-2026-23231 CVE-2026-3497 Original Bulletin: https://www.ibm.com/support/pages/node/7270299 Comment: CVSS (Max): 7.8 CVE-2026-23231 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) CVSS Source: IBM Calculator: https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H EPSS (Max): 0.7% (71st)* CVE-2026-23231 2026-05-07 * Not all EPSS found when published - --------------------------BEGIN INCLUDED TEXT-------------------- IBM Support Document Information Document number : 7270299 Modified date : More support for: IBM MQ Appliance Product : IBM MQ Appliance Component : - Software version : 9.4LTS; 9.4CD Operating system(s): Appliance Security Bulletin Summary IBM MQ Appliance has addressed multiple open source vulnerabilities. Vulnerability Details CVEID: CVE-2026-23193 DESCRIPTION: In the Linux kernel, the following vulnerability has been resolved: scsi: target: iscsi: Fix use-after-free in iscsit_dec_session_usage_count() In iscsit_dec_session_usage_count(), the function calls complete() while holding the sess-session_usage_lock. Similar to the connection usage count logic, the waiter signaled by complete() (e.g., in the session release path) may wake up and free the iscsit_session structure immediately. This creates a race condition where the current thread may attempt to execute spin_unlock_bh() on a session structure that has already been deallocated, resulting in a KASAN slab-use-after-free. To resolve this, release the session_usage_lock before calling complete() to ensure all dereferences of the sess pointer are finished before the waiter is allowed to proceed with deallocation. CWE: CWE-416: Use After Free CVSS Source: NVD CVSS Base score: 7.8 CVSS Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) CVEID: CVE-2026-23231 DESCRIPTION: In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: fix use-after-free in nf_tables_addchain() nf_tables_addchain() publishes the chain to table-chains via list_add_tail_rcu () (in nft_chain_add()) before registering hooks. If nf_tables_register_hook() then fails, the error path calls nft_chain_del() (list_del_rcu()) followed by nf_tables_chain_destroy() with no RCU grace period in between. This creates two use-after-free conditions: 1) Control-plane: nf_tables_dump_chains() traverses table-chains under rcu_read_lock(). A concurrent dump can still be walking the chain when the error path frees it. 2) Packet path: for NFPROTO_INET, nf_register_net_hook() briefly installs the IPv4 hook before IPv6 registration fails. Packets entering nft_do_chain() via the transient IPv4 hook can still be dereferencing chain-blob_gen_X when the error path frees the chain. Add synchronize_rcu() between nft_chain_del() and the chain destroy so that all RCU readers -- both dump threads and in-flight packet evaluation -- have finished before the chain is freed. CWE: CWE-416: Use After Free CVSS Source: NVD CVSS Base score: 7.8 CVSS Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) CVEID: CVE-2026-3497 DESCRIPTION: Vulnerability in the OpenSSH GSSAPI delta included in various Linux distributions. This vulnerability affects the GSSAPI patches added by various Linux distributions and does not affect the OpenSSH upstream project itself. The usage of sshpkt_disconnect() on an error, which does not terminate the process, allows an attacker to send an unexpected GSSAPI message type during the GSSAPI key exchange to the server, which will call the underlying function and continue the execution of the program without setting the related connection variables. As the variables are not initialized to NULL the code later accesses those uninitialized variables, accessing random memory, which could lead to undefined behavior. The recommended workaround is to use ssh_packet_disconnect() instead, which does terminate the process. The impact of the vulnerability depends heavily on the compiler flag hardening configuration. CWE: CWE-908: Use of Uninitialized Resource CVSS Source: security@ubuntu.com CVSS Base score: 6.9 CVSS Vector: (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/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 +-------------------+-----------------------------+ |Affected Product(s)|Version(s) | +-------------------+-----------------------------+ |IBM MQ Appliance |9.4 LTS - 9.4.0.0 to 9.4.0.20| +-------------------+-----------------------------+ |IBM MQ Appliance |9.4 CD - 9.4.1.0 to 9.4.5.0 | +-------------------+-----------------------------+ Remediation/Fixes This vulnerability is addressed under APAR DT468012 IBM strongly recommends addressing the vulnerability now. IBM MQ Appliance version 9.4 LTS Apply IBM MQ Appliance cumulative security update 9.4.0.21 , or later firmware. IBM MQ Appliance version 9.4 CD Apply IBM MQ Appliance cumulative security update 9.4.5.1 , or later firmware. Workarounds and Mitigations None Change History *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. In addition to other efforts to address potential vulnerabilities, IBM periodically updates the record of components contained in our product offerings. As part of that effort, if IBM identifies previously unidentified packages in a product/service inventory, we address relevant vulnerabilities regardless of CVE date. Inclusion of an older CVEID does not demonstrate that the referenced product has been used by IBM since that date, nor that IBM was aware of a vulnerability as of that date. We are making clients aware of relevant vulnerabilities as we become aware of them. "Affected Products and Versions" referenced in IBM Security Bulletins are intended to be only products and versions that are supported by IBM and have not passed their end-of-support or warranty date. Thus, failure to reference unsupported or extended-support products and versions in this Security Bulletin does not constitute a determination by IBM that they are unaffected by the vulnerability. Reference to one or more unsupported versions in this Security Bulletin shall not create an obligation for IBM to provide fixes for any unsupported or extended-support products or versions. - --------------------------END INCLUDED TEXT---------------------- You have received this e-mail bulletin as a result of your organisation's registration with AUSCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AUSCERT's members. As AUSCERT did not write the document quoted above, AUSCERT has had no control over its content. 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