From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-45923][LOW] net: usb: catc: enable basic endpoint checking [ Upstream Date: Wed, 27 May 2026 21:12:42 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-45923 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: 1 X-AL-KERNEL-ActionableScore-Lower: 0 X-AL-KERNEL-Commit: eade522d3e6ac3f3bfb51bfa5b5b4b32bd0b846f List-Id: CVE: CVE-2026-45923 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: net: usb: catc: enable basic endpoint checking [ Upstream Commit: eade522d3e6ac3f3bfb51bfa5b5b4b32bd0b846f Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=eade522d3e6ac3f3bfb51bfa5b5b4b32bd0b846f Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45923 Analysis date: Wed, 27 May 2026 21:12:42 -0400 ActionableScore: 1 ActionableScore lower bound: 0 Actionable bucket: Ordinary Moderate / Low-like Manual review required: NO Summary: A malformed physical USB device can expose mismatched endpoint descriptors to the `catc` USB Ethernet driver, causing incorrect URB setup assumptions and potential device-level availability impact. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-45923 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45923 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-2026-45923 LOW CHECK Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H';*CWE-20;CWE-754;CWE-693;Other CVSS 'AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.6';DESCR 'The catc USB Ethernet driver trusted fixed endpoint numbers without validating that the device descriptors actually provided the expected bulk and interrupt endpoint types. A malformed or malicious USB device could expose mismatched endpoint descriptors and make the driver submit URBs using incorrect pipe assumptions. For the CVSS the PR:N is used because no privileges on the target system are needed once the attacker can present the USB device, while the attack vector is physical rather than network reachable. Impact is primarily device or kernel availability risk from driver malfunction. No supported evidence indicates information disclosure, integrity impact, kernel memory corruption, or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1) MAYBE USB ERRORPATH NETWORK HARDWARE PACKET DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=1 ActionableScoreLower=0 ## 1. ActionableScore * Conservative score: 0 * Paranoid score: 1 * Final recommended bucket: **Ordinary Moderate / Low-like**:: ## 2. Signal breakdown * Availability impact realistic: +1 in paranoid scoring only A malformed USB device with mismatched endpoint descriptors may cause the driver to malfunction, fail probe, or potentially trigger USB/network device availability issues. * Physical-only or rare hardware-only condition: -2 The attacker must present a malformed or malicious physical USB device to the target system. * Rare AND difficult-to-reach subsystem/configuration: -1 conservative This affects the old `catc` USB Ethernet driver and requires matching hardware or malicious USB emulation that binds to this driver. * No remote/network trigger: +0 Despite being a network driver, the vulnerable path is USB device probing, not packet processing. * No memory corruption shown: +0 The patch shows missing endpoint descriptor validation, not UAF, OOB write, heap corruption, or arbitrary write. * No privilege escalation or confidentiality impact: +0 The commit does not support data disclosure, policy bypass, or LPE. ## 3. Reachability analysis The bug is reachable when a malformed USB device is physically attached and matched to the `catc` USB Ethernet driver. No local account or kernel privilege is needed if the attacker can plug in or emulate the USB device, but physical access is required. Containers and namespaces do not meaningfully change reachability because enumeration happens at the host USB subsystem level. The path is not network reachable. Realistic exploitation is limited to malicious peripheral scenarios, lab systems, kiosks, or devices where untrusted USB access is in scope. ## 4. Severity interpretation This behaves like Low or ordinary Moderate. It is an input validation bug in a kernel driver, but the demonstrated issue is endpoint type mismatch during probe and URB setup, with availability as the only supported impact. There is no evidence of kernel memory corruption, privilege escalation, or information disclosure. The old and specific driver plus physical access requirement keeps practical priority low. ## 5. One-sentence report phrase A malformed physical USB device can expose mismatched endpoint descriptors to the `catc` USB Ethernet driver, causing incorrect URB setup assumptions and potential device-level availability impact. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED The issue is physical-access dependent, driver-specific, and does not show memory corruption or privilege escalation. Manual review is only warranted for products where malicious USB peripherals are explicitly in scope. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: net: usb: catc: enable basic endpoint checking [ Upstream Commit: eade522d3e6ac3f3bfb51bfa5b5b4b32bd0b846f Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=eade522d3e6ac3f3bfb51bfa5b5b4b32bd0b846f Changed files: drivers/net/usb/catc.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=eade522d3e6ac3f3bfb51bfa5b5b4b32bd0b846f ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-45923 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45923 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:L The Best / paranoid CVSS vector: AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS score: 4.6 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: 0 Paranoid ActionableScore: 1 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).