From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-99154][MODERATE REGULAR] scsi: libiscsi: Reject a negative task index from parse_pdu_itt Date: Fri, 30 Oct 2026 10:44:15 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-99154 X-AL-KERNEL-Priority: MODERATE REGULAR X-AL-KERNEL-Severity: MODERATE REGULAR X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: NO X-AL-KERNEL-ActionableScore: 3 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: 6cadfa6f1f5896632d4223d3b7addb2a29fea74e List-Id: CVE: CVE-2026-99154 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: scsi: libiscsi: Reject a negative task index from parse_pdu_itt Commit: 6cadfa6f1f5896632d4223d3b7addb2a29fea74e Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6cadfa6f1f5896632d4223d3b7addb2a29fea74e Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99154 Analysis date: Fri, 30 Oct 2026 10:44:15 -0400 ActionableScore: 3 ActionableScore lower bound: unknown Actionable bucket: Borderline / manual review recommended Manual review required: YES Summary: A malicious iSCSI target can supply an ITT that becomes a negative be2iscsi task index, causing an OOB pointer read and potentially a host-kernel crash when the invalid task pointer is consumed. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-99154 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99154 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 REGULAR Manual review required: YES A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-99154 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-99154 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=2 LEGACY=MODERATE RESULT=DIFF (final Legacy and Aegis differ; FINAL: MODERATE, Aegis: MODERATE_KPANIC) Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H';CWE-125;CWE-129;*CWE-20;Other CVSS 'AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '6.4';DESCR 'A malicious or compromised iSCSI target can provide an ITT that becomes a negative task index in the be2iscsi parse path. The index passes the previous upper bound only checks and causes an out of bounds pointer read before session cmds. The resulting value may be used as an iscsi task pointer and can cause a kernel crash. For the CVSS the PR:N value is used because the remote target needs no privileges on the affected initiator, although an active iSCSI session and access to the storage network are required. The confirmed impact is availability loss. Limited confidentiality or integrity impact remains plausible if downstream task handling uses the invalid pointer, but no controlled arbitrary read or write primitive is established. Automated impact decision path. The original SimpleNet classifier selected LOW. The primary LLM estimated paranoid CVSS 6.4 and the production ActionableScore returned 3 with recommendation Borderline / manual review recommended. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage LOW to MODERATE_KPANIC because the manual review requirement was applied. ActionableScore thresholds stage MODERATE_KPANIC to MODERATE because the ActionableScore threshold 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 INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK and DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 and V41_INHERITED_KPANIC_PROMOTION_BLOCKED and MANUAL_REVIEW_REQUIRED. The independent weaker Aegis shadow evaluated CVSS 0.0 and ActionableScore 2 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. The models disagreed but the aggregation rules retained the production result. The final reported impact is MODERATE.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 3) MAYBE READ LEAK HARDWARE LINUS INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 V41_INHERITED_KPANIC_PROMOTION_BLOCKED MANUAL_REVIEW_REQUIRED - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=3 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: 3. * Conservative score: 3; no floor or cap applied. * Raw paranoid score: 3. * Paranoid score: 3; stronger confidentiality, integrity, or write effects lack sufficient evidence. * Final recommended bucket: **Borderline / manual review recommended**:: 2. Signal breakdown * +1 firmware-mediated external influence: a malicious iSCSI target supplies the ITT, but the vulnerable path is specifically mediated by the be2iscsi hardware async ring. * +1 weak/indirect corruption candidate: attacker-influenced ITT conversion can produce a negative index, read before `session->cmds`, and reinterpret the fetched value as an `iscsi_task` pointer. * +1 reliable kernel crash/strong DoS: downstream use of the invalid task pointer plausibly causes a kernel fault. * No OOB-write points: the confirmed primitive is an out-of-bounds pointer read, not a heap write. * No confidentiality or integrity points: no disclosure path, controlled pointer value, later directed write, or sensitive-state modification is shown. * No extra availability point: it would duplicate the same crash. * NEW52/B5-R does not apply: there is no retry-accumulated index and no confirmed OOB write. * No privilege penalty: the evidenced attacker is the remote iSCSI target, not an initiator host administrator. 3. Reachability analysis A malicious or compromised target participating in an active iSCSI session can provide the unsolicited NOP-In ITT. The be2iscsi transport forwards that target-controlled tag and reports an ineffective age value, allowing the negative index to pass both former upper-bound-only checks. Access requires an affected be2iscsi deployment, active session, and storage-network reachability, but no host UID 0, capability, namespace privilege, race, or separate vulnerability is shown. 4. Primitive and severity reading The exact primitive is a negative-index OOB read before the `session->cmds` pointer array, followed by possible consumption of the resulting value as an active task pointer. This is not a UAF, OOB write, controlled reclaim, or authorization bypass. The supported consequence is host crash; useful disclosure or state corruption remains theoretical because the supplied evidence does not identify the fetched pointer value or a concrete downstream read/write operation. This is therefore CLASS_C, not an Important-preserving Class B/A primitive. Auto-downgrade remains allowed, although manual validation of downstream task consumers is advisable. 5. One-sentence report phrase A malicious iSCSI target can supply an ITT that becomes a negative be2iscsi task index, causing an OOB pointer read and potentially a host-kernel crash when the invalid task pointer is consumed. 6. Manual review advice MANUAL CHECK RECOMMENDED Review downstream `iscsi_task` consumers for a concrete write or disclosure before concluding the impact is strictly crash-only. 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: scsi: libiscsi: Reject a negative task index from parse_pdu_itt Commit: 6cadfa6f1f5896632d4223d3b7addb2a29fea74e Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6cadfa6f1f5896632d4223d3b7addb2a29fea74e Commit description: A transport that implements parse_pdu_itt hands libiscsi an index taken from the PDU, and both lookups bound it from above only: if (i >= session->cmds_max) i and cmds_max are both int, so a negative index passes and session->cmds[i] is read from before the array. be2iscsi produces one. beiscsi_parse_pdu() assigns the raw tag, *index = (int)itt; and beiscsi_complete_pdu() forwards an unsolicited NOP-In from the hardware async ring without replacing its ITT, so the value is the target's. It also reports the session's own age rather than the one in the tag, which leaves the age comparison in iscsi_verify_itt() with nothing to reject. Bound the index from below in both lookups. Fixes: bfead3b ("[SCSI] be2iscsi: Adding msix and mcc_rings V3") Cc: stable@vger.kernel.org Reviewed-by: Mike Christie Signed-off-by: Yehyeong Lee Link: https://patch.msgid.link/20261007015842.634893-2-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=6cadfa6f1f5896632d4223d3b7addb2a29fea74e ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-99154 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99154 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: AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS vector: AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H The Best / paranoid CVSS score: 6.4 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: 3 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: NO Published priority for this report (same as in Subject): MODERATE REGULAR 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).