From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-74457][MODERATE REGULAR] can: peak_usb: add bounds check for USB channel index Date: Sat, 15 Aug 2026 08:51:31 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-74457 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: 2 X-AL-KERNEL-Commit: 825c903ca3c98cd0cf0e3de8ab8f2604a5339b3f List-Id: CVE: CVE-2026-74457 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: can: peak_usb: add bounds check for USB channel index Commit: 825c903ca3c98cd0cf0e3de8ab8f2604a5339b3f Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=825c903ca3c98cd0cf0e3de8ab8f2604a5339b3f Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74457 Analysis date: Sat, 15 Aug 2026 08:51:31 -0400 ActionableScore: 3 ActionableScore lower bound: 2 Actionable bucket: Borderline manual review recommended / physical-device Moderate Manual review required: YES Summary: A malicious or faulty PEAK PCAN-USB Pro compatible USB device can provide an out-of-range channel index that causes a heap out-of-bounds pointer read and invalid dereference in IRQ context, leading to a kernel crash. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-74457 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74457 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-2026-74457 MODERATE CHECK WITH IMPACT FROM ORIG NN MODERATE Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:P/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H';CWE-129;CWE-125;*CWE-20;**CWE-476;Other CVSS 'AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.7';DESCR 'A heap out-of-bounds read in the PEAK PCAN-USB Pro CAN driver occurs because ctrl_idx is derived from a USB device payload and only masked to 0-15 while usb_if dev has 2 entries. A malicious or faulty USB device can provide a channel index from 2 to 15, causing the driver to read past the device pointer array and later dereference an invalid pointer in IRQ context. For the CVSS the PR:N because the attacker does not need privileges on the host when the attack is modeled as a crafted USB device connected to the system. The issue is not network reachable and requires physical or equivalent USB device access. Impact is at least denial of service via kernel panic. The paranoid score keeps limited confidentiality and integrity impact because the primitive is a heap out-of-bounds read of a pointer followed by dereference, but the patch does not show an arbitrary write primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline manual review recommended / physical-device Moderate (with actual score 3) YES OOB DANGER USB SIMPLEFIX NETWORK SKB HARDWARE LINUS DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 NO NO guess ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=3 ActionableScoreLower=2 ## 1. ActionableScore * Conservative score: 2 * Paranoid score: 3 * Final recommended bucket: **Borderline manual review recommended / physical-device Moderate**:: ## 2. Signal breakdown Triggered signals: * Firmware-mediated or device-mediated external influence: +1 The index comes directly from a USB device payload, so a malicious or faulty USB device can influence the vulnerable path. * Memory corruption, weak/indirect corruption candidate: +1 The bug is an unchecked array index into `usb_if->dev[]`, producing a heap out-of-bounds read of a pointer and later invalid object interpretation. * Reliable kernel crash / strong DoS: +1 The commit explicitly says values 2-15 eventually cause kernel panic in IRQ context. * Privileged kernel/device-management memory corruption path: +1 The corruption occurs in a kernel USB CAN driver receive/error path fed by device data. Subtracted signals: * Physical-only or rare hardware-only condition: -2 Realistic triggering requires a malicious/faulty PEAK PCAN-USB Pro style USB device or equivalent USB device control. * Rare AND difficult-to-reach subsystem/configuration: -1 in conservative view This is a device-specific CAN USB driver path, not a broadly exposed default kernel interface. Paranoid adjustment: * The paranoid score avoids the rare-subsystem subtraction because USB device parsing bugs with kernel OOB pointer reads deserve manual review even when hardware-specific. * No strong LPE signal is awarded because the patch shows OOB read plus invalid pointer dereference, not controlled reclaim, arbitrary write, callback control, or object replacement. ## 3. Reachability analysis The attacker can trigger the bug by controlling the USB payload received by the affected PEAK PCAN-USB Pro driver. This normally means physical access to attach a malicious USB CAN device, compromised device firmware, or an equivalent virtual/USB-over-IP setup. No local Linux user privileges are required on the host if the attacker controls the USB device, but this is not network reachable in the normal TCP/IP sense. Namespaces and containers do not materially reduce the requirement, because the vulnerable input comes from hardware/device traffic rather than a namespaced local syscall API. The path is not default-exposed on most systems and requires the affected driver and matching hardware to be present. Call-site confidence: high, because the patch shows both vulnerable dereferences before `alloc_can_skb()` and CAN error handling in the affected receive paths. ## 4. Severity interpretation This behaves like an actionable physical-device Moderate rather than an Important-class kernel vulnerability. The theoretical concern is kernel memory safety, because a device-controlled index causes an out-of-bounds pointer read and bogus object dereference. The realistic demonstrated impact is kernel panic in IRQ context, i.e. host DoS. There is not enough evidence for strong privilege escalation: no OOB write, no attacker-controlled replacement object, no callback dispatch, no refcount takeover, and no demonstrated information disclosure path. Manual review is still recommended because device-controlled OOB pointer reads in kernel drivers can sometimes hide stronger object-confusion consequences. ## 5. One-sentence report phrase A malicious or faulty PEAK PCAN-USB Pro compatible USB device can provide an out-of-range channel index that causes a heap out-of-bounds pointer read and invalid dereference in IRQ context, leading to a kernel crash. ## 6. Manual review recommendation MANUAL CHECK RECOMMENDED Reason: the practical exposure is limited by physical or equivalent USB device access, but the bug is still a device-controlled kernel heap OOB read followed by invalid object dereference, so it should not be auto-closed without confirming no stronger object-confusion or write-side consequences exist. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: can: peak_usb: add bounds check for USB channel index Commit: 825c903ca3c98cd0cf0e3de8ab8f2604a5339b3f Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=825c903ca3c98cd0cf0e3de8ab8f2604a5339b3f Commit description: The channel control index ctrl_idx is derived from rx->len which comes directly from a device USB payload. The mask 0x0f allows values 0-15, but the array size of usb_if->dev[] is only 2. Values 2-15 cause heap out-of-bounds read, eventually causing kernel panic in the IRQ context. Add bounds checking for ctrl_idx before the array access in both pcan_usb_pro_handle_canmsg() and pcan_usb_pro_handle_error(). Fixes: d8a1993 ("can: usb: PEAK-System Technik PCAN-USB Pro specific part") Signed-off-by: James Gao Reviewed-by: Vincent Mailhol Link: https://patch.msgid.link/TYWPR01MB8559DBAAAA6A7F410400329CF0012@TYWPR01MB8559.jpnprd01.prod.outlook.com Cc: stable@kernel.org Signed-off-by: Marc Kleine-Budde Signed-off-by: Greg Kroah-Hartman Changed files: drivers/net/can/usb/peak_usb/pcan_usb_pro.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=825c903ca3c98cd0cf0e3de8ab8f2604a5339b3f ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-74457 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74457 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:L/PR:N/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS vector: AV:P/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H The Best / paranoid CVSS score: 5.7 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: 2 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).