From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-72083][IMPORTANT] scsi: target: core: Fix iSCSI ISID use-after-free in REGISTER AND MOVE Date: Sat, 15 Aug 2026 04:43:57 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-72083 X-AL-KERNEL-Priority: IMPORTANT X-AL-KERNEL-Severity: IMPORTANT X-AL-KERNEL-Base-Severity: IMPORTANT X-AL-KERNEL-KPANIC: NO X-AL-KERNEL-ActionableScore: 8 X-AL-KERNEL-ActionableScore-Lower: 6 X-AL-KERNEL-Commit: 7d56f5c868d92c9d504a34a3ea450bce481c7f63 List-Id: CVE: CVE-2026-72083 Priority: IMPORTANT AL-KERNEL base severity: IMPORTANT KPANIC flag: NO Patch: scsi: target: core: Fix iSCSI ISID use-after-free in REGISTER AND MOVE Commit: 7d56f5c868d92c9d504a34a3ea450bce481c7f63 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7d56f5c868d92c9d504a34a3ea450bce481c7f63 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72083 Analysis date: Sat, 15 Aug 2026 04:43:57 -0400 ActionableScore: 8 ActionableScore lower bound: 6 Actionable bucket: Strong Important candidate / Actionable Moderate at minimum Manual review required: YES Summary: A network-reachable use-after-free read in the Linux SCSI iSCSI target PR OUT REGISTER AND MOVE path can dereference an ISID pointer after the mapped parameter list is unmapped, causing at least remote kernel crash DoS and requiring manual review for possible limited C/I impact. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-72083 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72083 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: IMPORTANT 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-2026-72083 IMPORTANT CHECK WITH IMPACT FROM ORIG NN IMPORTANT Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H';*CWE-416;CWE-825;*CWE-664;Other CVSS 'AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '8.6';DESCR 'A use after free read exists in the SCSI target PR OUT REGISTER AND MOVE path because an iSCSI ISID pointer can alias the mapped parameter list and remain in use after transport_kunmap_data_sg() tears down the mapping. A remote iSCSI initiator can trigger this with a parameter list larger than one page, where the buffer may be mapped with vmap() and later unmapped with vunmap(), leaving iport_ptr as a stale kernel virtual pointer used by strcmp and reservation lookup or allocation logic. For the CVSS the PR:N is used for the paranoid score because an exposed iSCSI target may accept a network initiator without additional local privileges, while authenticated storage deployments may be better represented by PR:L. The issue is network reachable in environments where the iSCSI target port is reachable from an attacker controlled initiator. Impact is at least denial of service via kernel crash and in worst case may allow limited confidentiality or integrity impact due to stale pointer based parsing in kernel target code, so it should be reviewed manually.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 8) YES OOB ERRORPATH UAF NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=8 ActionableScoreLower=6 ## 1. ActionableScore * Conservative score: 6 * Paranoid score: 8 * Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**:: ## 2. Signal breakdown Conservative signals: * Remote reachable / network-triggerable: +2 The affected path is in the iSCSI SCSI target command handling path and can be reached by an iSCSI initiator that can send PR OUT REGISTER AND MOVE commands. * Memory corruption, weak/indirect corruption candidate: +1 The bug is an explicit stale pointer / use-after-free read of `iport_ptr` after `transport_kunmap_data_sg()` tears down the mapped parameter buffer. It is read-only in the shown path, so this is not treated as a strong overwrite primitive. * Real lifetime corruption: +1 `iport_ptr` aliases a mapped PR OUT parameter list and remains live after the mapping is destroyed by `vunmap()`. * Reliable kernel crash / strong DoS: +1 Subsequent dereferences in `strcmp()`, reservation lookup, or allocation logic can fault on an unmapped kernel virtual address. * Important filesystem/storage path: +1 This affects Linux SCSI target persistent reservation handling over iSCSI, a storage protocol path with operationally important availability impact. Paranoid additional signals: * Confidentiality impact plausible: +1 In a worst still-defensible interpretation, stale pointer based reads from a reused or invalid kernel virtual mapping could expose limited unintended data, although no direct leak primitive is demonstrated. * Integrity impact plausible: +1 The stale pointer influences reservation lookup and registration logic, so limited integrity impact is plausible in triage, but not proven as arbitrary write or privilege escalation. ## 3. Reachability analysis An attacker must be able to act as an iSCSI initiator against an affected Linux SCSI target and send a crafted PR OUT REGISTER AND MOVE command with a parameter list larger than one page. No local code execution on the target host is required if the iSCSI target portal is reachable over the network. In typical deployments, iSCSI targets are usually placed on isolated storage or data-center networks and may require initiator ACLs or authentication. That reduces Internet-scale exposure but does not remove network-triggerability in environments where an attacker has access to the storage network or a permitted initiator identity. Namespaces and containers are not the primary factor here. The relevant boundary is network/storage access to the iSCSI target service, not local Linux namespace privileges. Call-site confidence: high. The commit message identifies the stale pointer users after unmap, including `strcmp()`, `__core_scsi3_locate_pr_reg()`, and `core_scsi3_alloc_registration()`. ## 4. Severity interpretation This is not an ordinary Moderate cleanup because the patch fixes a concrete lifetime bug in a network-reachable kernel storage target path. The realistic impact is remote denial of service through a kernel fault or crash. Theoretical impact beyond DoS is weaker but not ignorable. The primitive is a stale pointer read, not a demonstrated write-after-free, object replacement, callback hijack, or arbitrary memory corruption. Therefore the conservative score stays in Actionable Moderate territory, while the paranoid score reaches Strong Important candidate due to network reachability plus explicit UAF/lifetime corruption in kernel target code. ## 5. One-sentence report phrase A network-reachable use-after-free read in the Linux SCSI iSCSI target PR OUT REGISTER AND MOVE path can dereference an ISID pointer after the mapped parameter list is unmapped, causing at least remote kernel crash DoS and requiring manual review for possible limited C/I impact. ## 6. Manual review recommendation MANUAL CHECK REQUIRED This is a network-reachable UAF/lifetime bug in kernel storage target code. The demonstrated impact is DoS, but the stale pointer is later used in reservation lookup and allocation logic, so it should not be auto-closed without manual review. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: scsi: target: core: Fix iSCSI ISID use-after-free in REGISTER AND MOVE Commit: 7d56f5c868d92c9d504a34a3ea450bce481c7f63 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7d56f5c868d92c9d504a34a3ea450bce481c7f63 Commit description: core_scsi3_emulate_pro_register_and_move() maps the PERSISTENT RESERVE OUT parameter list with transport_kmap_data_sg() and parses the destination TransportID with target_parse_pr_out_transport_id(). For an iSCSI TransportID (FORMAT CODE 01b), iscsi_parse_pr_out_transport_id() returns the ISID in iport_ptr as a raw pointer into that mapped buffer. The function then unmaps the buffer with transport_kunmap_data_sg() before dereferencing iport_ptr in strcmp(), __core_scsi3_locate_pr_reg() and core_scsi3_alloc_registration(). When the parameter list spans more than one page (PARAMETER LIST LENGTH > 4096), transport_kmap_data_sg() uses vmap() and transport_kunmap_data_sg() does vunmap(), so the kernel virtual address backing iport_ptr is torn down and every subsequent dereference is a use-after-free read of the unmapped region. Keep the parameter list mapped until iport_ptr is no longer needed: drop the early transport_kunmap_data_sg() and unmap once on the success path, right before returning. The error paths already unmap through the existing "if (buf) transport_kunmap_data_sg(cmd)" at the out: label, which now runs on every post-map error exit because buf is no longer cleared early. Only reads of the mapping happen while spinlocks are held; the map and unmap calls remain outside any lock. The sibling caller core_scsi3_decode_spec_i_port() already uses the buffer before unmapping it and is left unchanged. Fixes: 4949314 ("target: Allow control CDBs with data > 1 page") Cc: stable@vger.kernel.org Signed-off-by: Bryam Vargas Reviewed-by: John Garry Reviewed-by: David Disseldorp Link: https://patch.msgid.link/20260610042245.35473-1-hexlabsecurity@proton.me Signed-off-by: Martin K. Petersen Signed-off-by: Greg Kroah-Hartman Changed files: drivers/target/target_core_pr.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=7d56f5c868d92c9d504a34a3ea450bce481c7f63 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-72083 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72083 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:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS vector: AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H The Best / paranoid CVSS score: 8.6 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: 6 Paranoid ActionableScore: 8 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: IMPORTANT KPANIC detected for this report: NO Published priority for this report (same as in Subject): IMPORTANT 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).