From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-99152][MODERATE 7.0] scsi: libiscsi: Validate the task named by a management response Date: Thu, 29 Oct 2026 00:52:15 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-99152 X-AL-KERNEL-Priority: MODERATE 7.0 X-AL-KERNEL-Severity: MODERATE 7.0 X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: YES X-AL-KERNEL-ActionableScore: 1 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: 55a65ef61e2775aeb18fda63bd1959fa8b41f936 List-Id: CVE: CVE-2026-99152 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: YES Patch: scsi: libiscsi: Validate the task named by a management response Commit: 55a65ef61e2775aeb18fda63bd1959fa8b41f936 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=55a65ef61e2775aeb18fda63bd1959fa8b41f936 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99152 Analysis date: Thu, 29 Oct 2026 00:52:15 -0400 ActionableScore: 1 ActionableScore lower bound: unknown Actionable bucket: Ordinary Moderate Manual review required: NO Summary: A malicious connected iSCSI target can name an unused task slot in a management response and trigger a NULL-pointer dereference in the initiator kernel. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-99152 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99152 The original announcement does not normally provide a security severity estimate, CVSS assessment, or enough information to determine whether the reported kernel bug represents a practically relevant security issue. This report was generated by AL-KERNEL, an AI-assisted Linux kernel vulnerability analysis system developed by Alexander Larkin. It combines an autonomous classifier with LLM-assisted technical analysis and a separate ActionableScore mechanism. The purpose of this report is to prioritize Linux kernel CVEs before manual review, identify cases that require prompt investigation, and support automatic closure of issues that are unlikely to have meaningful security impact. Published priority for this report: MODERATE 7.0 Manual review required: NO A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-99152 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-99152 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=4 LEGACY=MODERATE_KPANIC RESULT=SAME V39_AEGIS_ONE_STEP_UP=MODERATE->MODERATE_KPANIC TEMP_DISTANCE_MERGE=LOW->MODERATE;AEGIS=MODERATE_KPANIC;GAP=2 (final reconciliation agrees; DECISION: both MODERATE_KPANIC) Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H';*CWE-20;**CWE-476;CWE-1285;BEST CVSS score: '6.5';DESCR 'An attacker controlled or compromised iSCSI target can send a management response with an in range ITT that identifies an unused task slot. iscsi_itt_to_task validates only the slot index, so the free task can reach iscsi_nop_out_rsp or iscsi_complete_task with task conn set to NULL and crash the initiator kernel. For the CVSS the PR:N value is selected because the target does not need an authenticated user account or privileges on the initiator after an iSCSI session has been established. AV:A is used because exploitation requires an established iSCSI connection to a malicious target or comparable access to the storage network path. The demonstrated primitive is a NULL pointer dereference with availability impact only and there is no supported UAF, OOB access, information disclosure, or write primitive. Automated impact decision path. The original SimpleNet classifier selected LOW. The primary LLM estimated paranoid CVSS 6.5 and the production ActionableScore returned 1 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were final reconciliation stage LOW to MODERATE_KPANIC because the cross model evidence reconciliation rule was applied. The legacy KP specialist has no review artifact for this run. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were TEMP_DISTANCE_MERGE and V39_AEGIS_ONE_STEP_UP and MANUAL_REVIEW_REQUIRED. The independent weaker Aegis shadow evaluated CVSS 6.5 and ActionableScore 4 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. Cross model aggregation changed the production result under an enabled evidence gated merge rule. The final reported impact is MODERATE_KPANIC.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1) MAYBE KASAN OOB NULLPTR INIT LEAK HARDWARE LINUS TEMP_DISTANCE_MERGE KPANIC V39_AEGIS_ONE_STEP_UP MANUAL_REVIEW_REQUIRED - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=1 PrimitiveClass=CLASS_C RealUAF=NO HostAdminRequired=NO NamespaceScopedPrivilege=NO ImportantCandidate=NO ManualReview=RECOMMENDED AutoDowngradeAllowed=YES RequiresHostUID0=NO AuthorizationDecisionBypass=NO ProtectedResourceImpact=NONE B4PendingReview=NO B4PendingConfirmed=NO 1. ActionableScore * Raw base score: 1. * Conservative score: 1; no floor or cap applied. * Raw paranoid score: 1. * Paranoid score: 1; no supported stronger primitive. * Final recommended bucket: **Ordinary Moderate**:: 2. Signal breakdown * +1 Reliable kernel crash: an in-range ITT can select an unused task whose `task->conn` is NULL; later `iscsi_nop_out_rsp()` or `iscsi_complete_task()` dereferences it, with an observed kernel Oops. * +0 Remote reachability: the malformed PDU arrives over TCP, but exploitation requires a previously established iSCSI session and privileged initiator-side provisioning, so the prompt’s unrestricted remote-reachability bonus is not met. * No UAF, OOB access/write, refcount mutation, shared-backing write, disclosure, authorization bypass, or attacker-controlled corruption is shown. * Extra availability was not awarded because it would double-count the same crash. * NEW52/B5-R does not apply: there is no retry-accumulated heap OOB write or later consumption of corrupted state. * NEW53/B3-PENDING and B4-PENDING do not apply. 3. Reachability analysis An attacker-controlled or compromised iSCSI target can send the response after an initiator has established a session. The target needs no host UID, capability, or namespace privilege for the packet-stage trigger. However, a separate host-privileged actor ordinarily provisions the iSCSI connection; this is genuine prior privileged setup, not proof that the remote target itself has host-admin powers. No race, special hardware, or retry sequence is required. 4. Primitive and severity reading The primitive is validation failure causing selection of a free task-pool slot, followed by a NULL-pointer dereference. This is invalid-state crash behavior, not a lifetime violation or memory-corruption primitive, so it is CLASS_C. The demonstrated effect is host availability loss. No useful effect remains after excluding the crash, and no confidentiality, integrity, or privilege-escalation path is supported. Therefore ImportantCandidate is NO and automatic Important-to-Moderate downgrade is allowed. 5. One-sentence report phrase A malicious connected iSCSI target can name an unused task slot in a management response and trigger a NULL-pointer dereference in the initiator kernel. 6. Manual review advice MANUAL CHECK RECOMMENDED Confirm product-specific iSCSI exposure and whether untrusted or compromise-prone targets can use established sessions. 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: scsi: libiscsi: Validate the task named by a management response Commit: 55a65ef61e2775aeb18fda63bd1959fa8b41f936 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=55a65ef61e2775aeb18fda63bd1959fa8b41f936 Commit description: __iscsi_complete_pdu() fetches the task for five response types from one place and checks only that the index resolved: case ISCSI_OP_LOGOUT_RSP: case ISCSI_OP_LOGIN_RSP: case ISCSI_OP_TEXT_RSP: case ISCSI_OP_SCSI_TMFUNC_RSP: case ISCSI_OP_NOOP_IN: task = iscsi_itt_to_task(conn, hdr->itt); if (!task) return ISCSI_ERR_BAD_ITT; iscsi_itt_to_task() bounds the index against cmds_max and looks at nothing else, so a target can name any slot in the pool, including one that has never been used. task->conn is then NULL, and both iscsi_nop_out_rsp() and iscsi_complete_task() dereference it. One unsolicited NOP-In is enough; a Text Response carrying the same ITT crashes in iscsi_complete_task() instead. Require the task to be in flight and not a SCSI command, the way iscsi_itt_to_ctask() does for the command opcodes. [ 6.298634] Oops: general protection fault, probably for non-canonical address 0xdffffc000000000c: 0000 [#1] SMP KASAN NOPTI [ 6.298642] KASAN: null-ptr-deref in range [0x0000000000000060-0x0000000000000067] [ 6.298652] CPU: 1 UID: 0 PID: 111 Comm: iscsistart Not tainted 7.2.0-rc5-ISCSI1-gf5098b6bae76 #1 PREEMPT(lazy) [ 6.298654] Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 6.298656] RIP: 0010:iscsi_nop_out_rsp.constprop.0+0x46/0x160 [ 6.298691] Code: c1 ea 03 48 83 ec 08 80 3c 02 00 0f 85 f5 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 6b 58 48 8d 7d 60 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 c0 00 00 00 48 8b 45 60 48 39 c3 74 50 48 b8 00 [ 6.298698] RSP: 0018:ffff88806c907be8 EFLAGS: 00010206 [ 6.298701] RAX: dffffc0000000000 RBX: ffff888006116800 RCX: 0000000000000020 [ 6.298702] RDX: 000000000000000c RSI: ffff88800525d578 RDI: 0000000000000060 [ 6.298703] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 [ 6.298706] R10: 0000000000000020 R11: 0000000000000000 R12: 0000000000000000 [ 6.298706] R13: 000000000000002e R14: ffff8880056eb440 R15: ffff888006116800 [ 6.298707] FS: 00007fc02d1c2740(0000) GS:ffff8880b29bc000(0000) knlGS:0000000000000000 [ 6.298710] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 6.298711] CR2: 000055fe3b56ddf8 CR3: 00000000053b9004 CR4: 0000000000770ef0 [ 6.298712] PKRU: 55555554 [ 6.298713] Call Trace: [ 6.298714] [ 6.298714] __iscsi_complete_pdu+0x13a8/0x22a0 [ 6.298758] iscsi_complete_pdu+0x54/0xa0 [ 6.298759] iscsi_tcp_hdr_recv_done+0x870/0x2c80 [ 6.298778] iscsi_tcp_recv_skb+0x31e/0xec0 [ 6.298800] iscsi_sw_tcp_recv+0x12f/0x390 [ 6.298804] __tcp_read_sock+0x1ab/0x810 [ 6.298812] iscsi_sw_tcp_data_ready+0x18b/0x510 [ 6.298814] tcp_rcv_established+0x1f56/0x3a00 [ 6.298842] tcp_v4_do_rcv+0x449/0x960 [ 6.298847] tcp_v4_rcv+0x2245/0x3bc0 Fixes: 7996a77 ("[SCSI] iscsi: add libiscsi") Cc: stable@vger.kernel.org Reviewed-by: Mike Christie Signed-off-by: Yehyeong Lee Link: https://patch.msgid.link/20261007015842.634893-4-yhlee@isslab.korea.ac.kr Signed-off-by: Martin K. Petersen (Oracle) Signed-off-by: Greg Kroah-Hartman Changed files: drivers/scsi/libiscsi.c Diff excerpt: Not included in this email. See the upstream URL for the full patch. Full patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=55a65ef61e2775aeb18fda63bd1959fa8b41f936 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-99152 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99152 The original CVE announcement normally does not include a security-level estimate. In particular, it may not contain a CVSS assessment, an impact level, or enough information to determine whether the reported bug is a practically relevant security issue. One purpose of this parallel CVE list is to provide that missing technical and prioritization information. The original goal of the AL-KERNEL project was to prioritize Linux kernel CVE analysis automatically before manual review. The system can also help identify non-security issues that may be suitable for automatic closure. This report was generated by AL-KERNEL, an AI-assisted Linux kernel vulnerability analysis system developed by Alexander Larkin. The first analysis stage combines an autonomous classifier with additional LLM-based analysis. The autonomous classifier runs locally on a CPU and is based on a backpropagation neural network. Together, these mechanisms produce a technical vulnerability description, identify likely weakness types, estimate CVSS severity, and provide input for ActionableScore. Two CVSS estimates are retained because incomplete kernel vulnerability information often permits more than one defensible interpretation: Conservative CVSS vector: Not available The Best / paranoid CVSS vector: AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS score: 6.5 The conservative vector represents a lower-impact interpretation. The Best/paranoid vector intentionally represents a plausible upper-bound interpretation and should not automatically be treated as demonstrated real-world impact. CVSS may also need to be adjusted for a particular Linux deployment, because actual reachability, privileges, enabled kernel configuration, hardware, namespaces, exposed device nodes, and other environmental conditions can differ significantly between systems. A separate ActionableScore mechanism evaluates practical remediation urgency. Its analysis may include reachability, attack prerequisites, subsystem exposure, memory-corruption characteristics, denial-of-service reliability, and possible confidentiality, integrity, or privilege-escalation impact. Conservative ActionableScore: unknown Paranoid ActionableScore: 1 The final base severity is taken directly from the second tab-separated field of the AL-KERNEL classification result. ActionableScore does not replace or independently override that final AL-KERNEL decision, and if ActionableScore adjusted impact level of ALKERNEL, then you would see self-readable flags above like INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7. For an AL-KERNEL result of MODERATE, this report uses the following additional presentation split: ActionableScore below 5 -> MODERATE REGULAR ActionableScore 5 or more -> MODERATE 7.0 The distinction between MODERATE REGULAR and MODERATE 7.0 makes it possible to identify Moderate issues that should receive manual analysis and fixes before lower-priority MODERATE REGULAR issues. In many cases, MODERATE REGULAR fixes may wait for a later rebase or routine update. There is one override in which MODERATE REGULAR becomes MODERATE 7.0 even when the ActionableScore is below 5. When the AL-KERNEL result contains the KPANIC flag, a MODERATE result is always presented as MODERATE 7.0. The KPANIC flag selected with few regexps without usage of AI at all, so it helps to detect cases when Kernel Crash happens and similar (to filter False-Negative results from the LLM usage). KPANIC indicates that a reliable kernel crash, kernel panic, or similarly serious kernel availability impact was identified by the classification workflow. AL-KERNEL base severity for this report: MODERATE KPANIC detected for this report: YES Published priority for this report (same as in Subject): MODERATE 7.0 These results are intended to support engineering triage. They are machine-generated estimates, and cases marked for manual review should be validated by a human security engineer before final disposition. For more info read docs linked from here: https://kernelcve.org/ (and you can submit you own patch there to generate such a report for non-existant CVE-id yet). Note that in many cases this AI tool selects higher severity, than real is (means you can expect Importants instead of Moderate 7.0 or Moderates 7.0 instead of regular Moderates). If you see such cases, please use reply email interface to add additional manual analyses info to this particular CVE. And please, please, let me know when you see Lows instead of Importants or Important instead of Low (because particular for such cases I need to tune this AI tool to make it better for this one and next similar). My contact email for such notifications is alexanjelausa@gmail.com (and both send reply to CVE record itself too and see "reply" button below for howto reply).