From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-64334][LOW] USB: serial: digi_acceleport: fix hard lockup on disconnect Date: Sat, 25 Jul 2026 07:23:34 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-64334 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: 6e51147c2744d15730084dc89cc99180d3de4184 List-Id: CVE: CVE-2026-64334 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: USB: serial: digi_acceleport: fix hard lockup on disconnect Commit: 6e51147c2744d15730084dc89cc99180d3de4184 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6e51147c2744d15730084dc89cc99180d3de4184 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64334 Analysis date: Sat, 25 Jul 2026 07:23:34 -0400 ActionableScore: 2 ActionableScore lower bound: 1 Actionable bucket: Ordinary Moderate / Low-like Manual review required: NO Summary: A persistent OOB write URB submission failure in the `digi_acceleport` USB serial driver can cause an infinite loop with interrupts disabled during a disconnect race, leading to a local or physical denial of service via hard lockup. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-64334 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64334 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-2026-64334 LOW CHECK WITH IMPACT FROM ORIG NN MODERATE 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-835;**CWE-400;CWE-755;Other CVSS 'AV:P/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '4.7';DESCR 'digi_acceleport can enter an infinite loop with interrupts disabled when OOB write URB submission fails persistently during a disconnect race. A local user with access to the USB serial port may trigger the vulnerable path by racing open(), set_termios(), or close() with device removal or another condition that makes usb_submit_urb fail. For the CVSS the PR:L value is used for the paranoid score because reliable triggering can require only a local user context with access to the tty or USB serial device rather than full administrator privileges. The issue is not network reachable and requires local or physical interaction with the affected USB serial device. Impact is denial of service via hard lockup only. There is no evidence of UAF, OOB access, information disclosure, or privilege escalation from this patch context.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 2) YES WRITE OOB DEADLOCK USB PRINTF-TTY SIMPLEFIX RACE HARDWARE LINUS DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=2 ActionableScoreLower=1 ## 1. ActionableScore * Conservative score: 1 * Paranoid score: 2 * Final recommended bucket: **Ordinary Moderate / Low-like** ## 2. Signal breakdown Triggered positive signals: * Reliable kernel crash / strong DoS: +1 Persistent `usb_submit_urb()` failure can keep the loop running with interrupts disabled, causing a hard lockup. * Availability impact realistic: +1 in paranoid scoring The impact can be host-visible hard lockup rather than a minor local failure. This is counted only in the paranoid score to avoid double-counting ordinary crash impact. * Local unprivileged trigger: +1 in paranoid scoring A local user with access to the affected USB serial tty may be able to race `open()`, `set_termios()`, or `close()` with disconnect or another URB submission failure condition. Negative signals: * Hard or unreliable race / special timing required: -1 The issue depends on a race with disconnect or persistent URB submission failure. * Physical-only or rare hardware-only condition: -2 conservative, partially relaxed in paranoid scoring The clearest trigger involves a specific USB serial device and disconnect behavior. * Rare AND difficult-to-reach subsystem/configuration: -1 `digi_acceleport` is a legacy USB serial driver and not a broad/default kernel attack surface. No triggered signals: * No generic memory corruption. * No UAF, OOB write, double free, type confusion, refcount abuse, or page-cache/shared-page corruption. * No plausible privilege escalation primitive. * No network reachability. ## 3. Reachability analysis The realistic trigger requires the affected Digi AccelePort USB serial driver, an attached or disconnecting compatible USB serial device, and an operation that sends OOB commands while `usb_submit_urb()` persistently fails. The most explicit scenario is physical or local interaction with the USB device during `open()`, `set_termios()`, or `close()`. Namespaces and containers do not meaningfully broaden exposure unless the USB serial device node is delegated into the container. The path is not network reachable and is not a common default remote attack surface. Call-site confidence: high. The commit message directly names the relevant call situations and the patch shows the loop condition and missing error break. ## 4. Severity interpretation This behaves like an ordinary Moderate / Low-like kernel DoS issue rather than an Important-class vulnerability. The theoretical impact is severe availability loss via hard lockup, but the exploitation conditions are narrow and hardware/local-interaction dependent. There is no evidence of memory corruption, information disclosure, privilege escalation, or a reusable exploit primitive beyond denial of service. ## 5. One-sentence report phrase A persistent OOB write URB submission failure in the `digi_acceleport` USB serial driver can cause an infinite loop with interrupts disabled during a disconnect race, leading to a local or physical denial of service via hard lockup. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED Reason: the bug is DoS-only, hardware-specific, not network reachable, and the patch does not indicate memory corruption or privilege escalation potential. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: USB: serial: digi_acceleport: fix hard lockup on disconnect Commit: 6e51147c2744d15730084dc89cc99180d3de4184 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6e51147c2744d15730084dc89cc99180d3de4184 Commit description: If submitting the OOB write urb fails persistently (e.g if the device is being disconnected) the driver would loop indefinitely with interrupts disabled. Check for urb submission errors when sending OOB commands to avoid hanging if, for example, open(), set_termios() or close() races with a physical disconnect. This is issue was flagged by Sashiko when reviewing an unrelated change to the driver. Link: https://sashiko.dev/#/patchset/20260610132232.356139-1-johan%40kernel.org?part=1 Fixes: 1da177e ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Reviewed-by: Greg Kroah-Hartman Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman Changed files: drivers/usb/serial/digi_acceleport.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=6e51147c2744d15730084dc89cc99180d3de4184 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-64334 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64334 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:P/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H 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).