From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-53195][MODERATE 7.0] USB: serial: io_ti: fix heap overflow in build_i2c_fw_hdr() Date: Thu, 25 Jun 2026 06:20:26 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-53195 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: 7 X-AL-KERNEL-ActionableScore-Lower: 4 X-AL-KERNEL-Commit: 3e187152f44d76d7633a3855ffd0099e1588b82a List-Id: CVE: CVE-2026-53195 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: YES Patch: USB: serial: io_ti: fix heap overflow in build_i2c_fw_hdr() Commit: 3e187152f44d76d7633a3855ffd0099e1588b82a Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3e187152f44d76d7633a3855ffd0099e1588b82a Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53195 Analysis date: Thu, 25 Jun 2026 06:20:26 -0400 ActionableScore: 7 ActionableScore lower bound: 4 Actionable bucket: Strong Important candidate / Actionable Moderate at minimum Manual review required: YES Summary: A crafted io_ti firmware image can set an oversized Length field and trigger a kernel heap overflow in build_i2c_fw_hdr(), requiring firmware input control in typical deployments but posing a credible local privilege escalation risk if that control is delegated. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-53195 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53195 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-2026-53195 MODERATE CHECK Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H';CWE-122;*CWE-787;*CWE-20;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H';BEST CVSS score: '7.8';DESCR 'USB serial io_ti has a heap overflow in build_i2c_fw_hdr() because a firmware supplied Length field is used as the memcpy size without checking that it fits after struct ti_i2c_firmware_rec in the fixed allocation. A crafted firmware image can make the copy exceed the heap buffer and corrupt adjacent kernel memory during firmware processing for the io_ti driver. For the CVSS the PR:L is used for the paranoid score because normal systems require administrator control of firmware files, but some deployments may delegate firmware loading or device management to a less trusted local service or container root. The issue is not network reachable and requires local control over the firmware input or the firmware loading path. Impact may include kernel crash and, because this is a controlled heap overflow in kernel memory, potential privilege escalation should be considered for manual review.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 6) YES USB PRINTF-TTY SIMPLEFIX LINUS KPANIC INCREASED_TO_HIGH_BASED_ON_GUESSCVSS KPANIC DECREASED_TO_MODERATE70_BASED_ON_ACTIONABLESCORELOWERTHAN7 NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=7 ActionableScoreLower=4 ## 1. ActionableScore * Conservative score: 4 * Paranoid score: 7 * Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**:: ## 2. Signal breakdown Conservative signals: * Memory corruption, Strong corruption primitive: +2. The patch fixes a kernel heap overflow caused by copying a firmware-controlled Length field into a fixed-size heap buffer. * Reliable kernel crash / strong DoS: +1. A heap overflow in kernel memory is realistically crashable even if privilege escalation is not demonstrated. * Privileged kernel/device-management memory corruption path: +1. The corruption occurs in a USB serial driver firmware-processing path. * Requires admin/root in typical deployments: -2. Normal firmware files are controlled by root under the host firmware path. * Rare AND difficult-to-reach subsystem/configuration: -1. io_ti USB serial hardware and its firmware-loading path are not broad default exposure. Paranoid additional interpretation: * Firmware-mediated external influence: +1. The vulnerable input is a firmware image processed by the kernel driver. * Local lower-privilege trigger possible in delegated environments: +1. Some systems may delegate firmware/device management to service accounts, container root, or reduced-capability administrative contexts. * Privilege escalation plausible: +2. This is a controlled heap overflow in kernel memory, which is a credible LPE candidate if an attacker can influence the firmware image. * Do not apply the full admin penalty in the paranoid case. The relevant risk is reduced-privilege firmware or device-management control, not full host-root equivalence. ## 3. Reachability analysis The bug is not network reachable. The realistic trigger requires causing the io_ti driver to process a crafted firmware image with an oversized image Length field. In normal deployments this usually requires root or administrator control over the firmware file path and access to the relevant USB serial device or driver load path. Namespaces and containers matter only if device or firmware management is delegated. A regular unprivileged container normally cannot replace host firmware or bind arbitrary USB serial devices. A privileged container, reduced-capability root, firmware update service, or device-management daemon could lower the practical PR from full administrator to a weaker local privilege level. The subsystem is not broadly exposed by default, but the primitive is strong once reached. ## 4. Severity interpretation This is not an ordinary Moderate validation bug. The patch fixes a concrete heap overflow in kernel memory, not just a warning, leak, or NULL dereference. Realistic exploitation is gated by firmware control, so the conservative score stays borderline/manual-review rather than automatically Important. The paranoid score is Important-candidate because controlled kernel heap corruption can plausibly support LPE when the firmware-loading path is reachable by a less trusted local actor. There is no evidence of remote exploitation, but the memory corruption primitive is strong enough that this should not be auto-closed. ## 5. One-sentence report phrase A crafted io_ti firmware image can set an oversized Length field and trigger a kernel heap overflow in build_i2c_fw_hdr(), requiring firmware input control in typical deployments but posing a credible local privilege escalation risk if that control is delegated. ## 6. Manual review recommendation MANUAL CHECK REQUIRED Reason: this is a kernel heap overflow with attacker-influenced length and payload source. Even though typical reachability requires privileged firmware control, delegated firmware or device-management scenarios make the issue actionable and unsuitable for automatic closure. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: USB: serial: io_ti: fix heap overflow in build_i2c_fw_hdr() Commit: 3e187152f44d76d7633a3855ffd0099e1588b82a Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3e187152f44d76d7633a3855ffd0099e1588b82a Commit description: build_i2c_fw_hdr() allocates a fixed-size buffer of (16*1024 - 512) + sizeof(struct ti_i2c_firmware_rec) bytes, then copies le16_to_cpu(img_header->Length) bytes into it without validating that Length fits within the available space after the firmware record header. img_header->Length is a __le16 from the firmware file and can be up to 65535. check_fw_sanity() validates the total firmware size but not img_header->Length specifically. Fix by rejecting images where img_header->Length exceeds the available destination space. Fixes: 1da177e ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Adrian Korwel Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman Changed files: drivers/usb/serial/io_ti.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=3e187152f44d76d7633a3855ffd0099e1588b82a ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-53195 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53195 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:L/PR:H/UI:N/S:U/C:H/I:H/A:H The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H The Best / paranoid CVSS score: 7.8 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: 7 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).