From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2025-22068][MODERATE 7.0] ublk: make sure ubq->canceling is set when queue is frozen [ Upstream Date: Mon, 12 Oct 2026 21:59:55 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2025-22068 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: 5 X-AL-KERNEL-ActionableScore-Lower: 4 X-AL-KERNEL-Commit: 7e3497d7dacb5aee69dd9be842b778083cae0e75 List-Id: CVE: CVE-2025-22068 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: YES Patch: ublk: make sure ubq->canceling is set when queue is frozen [ Upstream Commit: 7e3497d7dacb5aee69dd9be842b778083cae0e75 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7e3497d7dacb5aee69dd9be842b778083cae0e75 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2025-22068 Analysis date: Mon, 12 Oct 2026 21:59:55 -0400 ActionableScore: 5 ActionableScore lower bound: 4 Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review Manual review required: YES Summary: No one-sentence report phrase was found. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2025-22068 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2025-22068 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: YES A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2025-22068 MODERATE https://www.kernelcve.org/list/?q=CVE-2025-22068 CHECK WITH IMPACT FROM ORIG NN IMPORTANT | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=4 LEGACY=MODERATE_KPANIC RESULT=SAME (legacy and Aegis reconciliation agree; DECISION: both MODERATE_KPANIC) Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H';*CWE-416;CWE-362;*CWE-664;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'A race in the ublk request cancellation path can allow ublk_queue_rq() to access a uring_cmd after that command has already been completed and freed. The issue occurs because ubq canceling may not be visible at the required point while the queue is being frozen, canceled, and later unfrozen. The demonstrated primitive is a use after free in an asynchronous io_uring and block request path. This can cause a kernel crash and local denial of service. In a worst case interpretation, reuse of the freed kernel object may also permit confidentiality or integrity impact and potential privilege escalation, although a reliable write primitive is not demonstrated. For the CVSS the PR:L value is used because a local ublk server or an unprivileged user on systems that permit unprivileged ublk devices may reach the affected path without full administrative control. AV:L applies because the issue requires local ublk and io_uring interaction and is not directly network reachable. AC:H applies because successful triggering depends on a timing window between request dispatch, queue freeze, cancellation, and command completion.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 5) MAYBE LOCK INIT UAF IO_URING KPANIC DECREASED_TO_MODERATE7_BASED_ON_FALSEPOSCHECKOFDH - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=5 ActionableScoreLower=4 PrimitiveClass=CLASS_B RealUAF=YES HostAdminRequired=NO NamespaceScopedPrivilege=NO ImportantCandidate=YES ManualReview=REQUIRED AutoDowngradeAllowed=NO RequiresHostUID0=NO AuthorizationDecisionBypass=NO ProtectedResourceImpact=NONE B4PendingReview=NO B4PendingConfirmed=NO 1. ActionableScore * Raw conservative score: 4 * Conservative score: 4 * Raw paranoid score: 5 * Paranoid score: 5 * No floor or cap changed either score. * Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**:: 2. Signal breakdown Conservative signals: * +2 Real UAF. The commit directly states that `ublk_queue_rq()` can touch a completed and freed `uring_cmd` when `ubq->canceling` is not published while the queue is frozen. * +1 Reliable kernel crash or strong DoS. Dereferencing or asynchronously completing a freed command can realistically cause an Oops or kernel crash. * +1 Local unprivileged trigger. ublk supports user-owned unprivileged devices, and the owning userspace server controls submission and cancellation of its `uring_cmd` requests without requiring host-admin-equivalent power. Paranoid-only signal: * +1 Attacker-influenced active-object lifetime manipulation. A ublk server controls command submission and can drive queue cancellation or server teardown while requests remain active. This gives repeated influence over the lifetime transition that creates the stale-use window. Not awarded: * No race penalty. The patch establishes an ordering and visibility defect, but does not show a narrow, one-shot, or externally uncontrollable timing window. * No Structured stale-object leverage point. The stale object is active and structured, but controlled reclaim, attacker-shaped replacement contents, and security-relevant field consumption after reuse are not established. * No Strong or Weak LPE point. Potential privilege escalation follows only from the generic UAF possibility, not from a demonstrated reclaim, callback, directed write, or refcount takeover. * No arbitrary or directed write is demonstrated. * No confidentiality or integrity point is awarded merely because reclaimed memory could theoretically be reused. * No extra Availability point is awarded because it would duplicate the same kernel-crash consequence. * No remote-reachability point is awarded. * No concrete repeated release or refcount point is awarded. The patch shows post-completion stale use, not a first release followed by a second lifetime-mutating release on the exact same reference. * Paranoid repeated-refcount leverage is therefore withheld. * FLOOR 5 is not applied mechanically. The paranoid score reaches 5 through attacker influence over active command lifetime, not through a repeated-release floor. * B5-R does not apply because no retry-accumulated heap OOB write is present. * B3-PENDING does not apply because no shared-backing write is present. * B4-PENDING does not apply because no authorization decision changes from DENY to ALLOW. 3. Reachability analysis The relevant attacker is a local ublk userspace server controlling a device and its io_uring commands. ublk has an unprivileged-device mode under which the device owner can submit requests and exercise cancellation or teardown without host UID 0 or host-admin-equivalent capabilities. Device-node permissions and feature availability remain deployment prerequisites, but host administration is not intrinsic to the vulnerable operation. The trigger does not depend on a namespace-scoped capability, so `NamespaceScopedPrivilege=NO`. No network input directly reaches this path. No special physical hardware is required because ublk is a software block driver. The attacker can submit repeated requests and influence cancellation or server termination, making repeated attempts practical. The evidence does not establish that an exact narrow race must be won. 4. Primitive and severity interpretation The exact primitive is a post-lifetime use of a completed `uring_cmd`. `ublk_queue_rq()` relies on `ubq->canceling` to decide whether normal asynchronous dispatch remains valid. If cancellation completes commands before that state is reliably visible, request dispatch can touch an already freed command. This is an active structured-object UAF rather than fixed stale DMA storage. It occurs in request dispatch and asynchronous completion handling, not solely in a cleanup destructor. However, the supplied code does not establish controlled reclaim, attacker-selected replacement data, callback control, arbitrary kernel read or write, or a completed privilege-escalation chain. There is no concrete repeated release/refcount operation. The first completion can end the command lifetime, but the later operation is described as touching or dispatching through the stale command rather than performing a verified second `put`, `free`, or refcount mutation on the exact reference. The demonstrated consequence is local kernel crash or DoS. Privilege escalation remains speculative. The issue is CLASS_B because a real active-object lifetime violation exists, but evidence is insufficient for CLASS_A. `ImportantCandidate=YES` and `AutoDowngradeAllowed=NO` are selected because a below-host-admin actor can influence an active asynchronous command lifetime and the resulting post-free processing has not been sufficiently characterized to exclude meaningful exploitation leverage. This preserves the issue for Important-versus-Moderate review without asserting proven LPE. 5. One-sentence report phrase A local ublk server can trigger a race in queue cancellation that lets request dispatch access a completed and freed uring_cmd, causing a kernel UAF and potential host crash while stronger exploitation remains unresolved. 6. Manual review recommendation MANUAL CHECK REQUIRED The active `uring_cmd` UAF is reachable through a user-controlled asynchronous block-request lifecycle, but reclaim behavior and the exact stale fields consumed by the later dispatch path require source-level review. 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: ublk: make sure ubq->canceling is set when queue is frozen [ Upstream Commit: 7e3497d7dacb5aee69dd9be842b778083cae0e75 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7e3497d7dacb5aee69dd9be842b778083cae0e75 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=7e3497d7dacb5aee69dd9be842b778083cae0e75 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2025-22068 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2025-22068 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:L/UI:N/S:U/C:L/I:L/A:H The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H The Best / paranoid CVSS score: 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: 4 Paranoid ActionableScore: 5 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).