From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-53124][LOW] ublk: reset per-IO canceled flag on each fetch [ Upstream Date: Wed, 24 Jun 2026 15:50:14 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-53124 X-AL-KERNEL-Priority: LOW X-AL-KERNEL-Severity: LOW X-AL-KERNEL-Base-Severity: LOW X-AL-KERNEL-KPANIC: NO X-AL-KERNEL-ActionableScore: 2 X-AL-KERNEL-ActionableScore-Lower: 1 X-AL-KERNEL-Commit: 63335e5a67d89bb7cb9b023bbb3785896587a648 List-Id: CVE: CVE-2026-53124 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: ublk: reset per-IO canceled flag on each fetch [ Upstream Commit: 63335e5a67d89bb7cb9b023bbb3785896587a648 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=63335e5a67d89bb7cb9b023bbb3785896587a648 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53124 Analysis date: Wed, 24 Jun 2026 15:50:14 -0400 ActionableScore: 2 ActionableScore lower bound: 1 Actionable bucket: Ordinary Moderate / Low-like storage DoS Manual review required: NO Summary: A ublk per-IO cancellation state bug can leave fetched commands permanently incomplete if the userspace server dies during recovery, causing local denial of service for the affected ublk device without evidence of memory corruption or privilege escalation. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-53124 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53124 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: LOW 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-2026-53124 LOW CHECK Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';*CWE-664;CWE-404;CWE-755;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'A ublk cancellation state bug can leave outstanding fetch commands permanently incomplete when a ublk server starts device recovery and dies after fetching only a nonempty subset of queue IOs. The per IO canceled flag can remain set even after a fetch command has been submitted, which prevents ublk_cancel_cmd from completing the outstanding io_uring command with io_uring_cmd_done(). This can stall cancellation and recovery for the affected ublk device and can cause denial of service for storage served by that device. For the CVSS the PR:L is used in the paranoid score because ublk can be driven by a local userspace server and some deployments allow reduced capability or unprivileged ublk daemons, even though initial device setup may be administrative. The issue is not network reachable and requires local control over the ublk server or recovery path. Impact is availability only.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like storage DoS (with actual score 2) SKIP CVE-2026-53124 SKIP The Fixes patch not applied yet, so unlikely that actual: 728cbac5fe219d3b8a21a0688a08f2b7f8aeda2b YES NO NO unknown MAYBE LOCK SIMPLEFIX HARDWARE IO_URING DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=2 ActionableScoreLower=1 ## 1. ActionableScore * Conservative score: 1 * Paranoid score: 2 * Final recommended bucket: **Ordinary Moderate / Low-like storage DoS** ## 2. Signal breakdown * Reliable device-level DoS / stuck recovery: +1 The bug can leave outstanding ublk fetch commands permanently incomplete, blocking cancellation and recovery for the affected device. * Important filesystem/storage path: +1 ublk is a block-device path, and the impact affects storage served by the userspace block driver. * Local high-control kernel data-plane API: +1 in paranoid interpretation ublk is driven through userspace interaction and io_uring command paths, but the demonstrated issue is state bookkeeping rather than memory corruption. * Hard or special lifecycle condition required: -1 Triggering requires recovery, partial fetch completion for a nonempty subset of queue IOs, and server death before all IOs are fetched. * Requires admin or device-management privileges in typical deployments: -2 conservative Creating and managing ublk devices is normally privileged, although some deployments may use reduced-capability or unprivileged ublk daemons. * Rare or configuration-dependent subsystem: -1 conservative ublk is not a default broad-exposure subsystem on most systems. No generic memory corruption, UAF, double-free, OOB write, page-cache corruption, or security-boundary bypass is supported by the patch. ## 3. Reachability analysis The bug is local and requires control over a ublk server or its recovery lifecycle. It is not network reachable. In typical deployments, setting up and managing ublk devices requires administrative or device-management privileges, so conservative scoring applies a privilege penalty. In a more paranoid deployment model, an unprivileged or reduced-capability ublk daemon may make the recovery failure path reachable by a less privileged local process, but the impact remains availability-only. ## 4. Severity interpretation This behaves like an ordinary Moderate or Low-like local storage DoS, not an Important-class kernel vulnerability. The patch fixes stale cancellation state for per-IO bookkeeping and does not indicate memory lifetime corruption or attacker-controlled overwrite. Theoretical impact is a stuck device recovery path. Realistic impact is denial of service for the affected ublk-backed storage, not privilege escalation. ## 5. One-sentence report phrase A ublk per-IO cancellation state bug can leave fetched commands permanently incomplete if the userspace server dies during recovery, causing local denial of service for the affected ublk device without evidence of memory corruption or privilege escalation. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED This can be auto-closed for urgent-security triage because it is a local, configuration-dependent ublk recovery DoS with no supported memory corruption, confidentiality impact, integrity impact, or privilege-escalation primitive. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: ublk: reset per-IO canceled flag on each fetch [ Upstream Commit: 63335e5a67d89bb7cb9b023bbb3785896587a648 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=63335e5a67d89bb7cb9b023bbb3785896587a648 Changed files: drivers/block/ublk_drv.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=63335e5a67d89bb7cb9b023bbb3785896587a648 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-53124 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53124 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:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS score: 4.7 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: 1 Paranoid ActionableScore: 2 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: LOW KPANIC detected for this report: NO Published priority for this report (same as in Subject): LOW 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).