From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-53148][IMPORTANT] thunderbolt: Clamp XDomain response data copy to allocation size Date: Thu, 25 Jun 2026 19:24:26 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-53148 X-AL-KERNEL-Priority: IMPORTANT X-AL-KERNEL-Severity: IMPORTANT X-AL-KERNEL-Base-Severity: IMPORTANT X-AL-KERNEL-KPANIC: YES X-AL-KERNEL-ActionableScore: 8 X-AL-KERNEL-ActionableScore-Lower: 7 X-AL-KERNEL-Commit: 0b334279a82d79fb4723bd4f614305de1ab69caa List-Id: CVE: CVE-2026-53148 Priority: IMPORTANT AL-KERNEL base severity: IMPORTANT KPANIC flag: YES Patch: thunderbolt: Clamp XDomain response data copy to allocation size Commit: 0b334279a82d79fb4723bd4f614305de1ab69caa Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0b334279a82d79fb4723bd4f614305de1ab69caa Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53148 Analysis date: Thu, 25 Jun 2026 19:24:26 -0400 ActionableScore: 8 ActionableScore lower bound: 7 Actionable bucket: Strong Important candidate / Actionable Moderate at minimum Manual review required: YES Summary: A malicious Thunderbolt XDomain peer can provide an oversized response length that causes `tb_xdp_properties_request()` to copy past a `kcalloc` buffer, resulting in kernel heap corruption with realistic DoS and plausible privilege-escalation impact. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-53148 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53148 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: IMPORTANT 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-2026-53148 IMPORTANT CHECK Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H';*CWE-787;CWE-122;*CWE-20;CWE-120;Other CVSS 'AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '8.8';DESCR 'A kernel heap out-of-bounds write exists in the Thunderbolt XDomain properties request path because tb_xdp_properties_request() copies response data using a length taken from the peer response header without ensuring that the cumulative offset stays within the allocated data buffer. A malicious XDomain peer can advertise a response length larger than the declared data_length and cause memcpy to write past the kcalloc allocation. For the CVSS the PR:N is used because the attacker does not need an account or privileges on the victim once a malicious peer can communicate on the local Thunderbolt/USB4 fabric. The issue is not Internet reachable and should be treated as adjacent local-bus exposure rather than AV:N. Impact is at least denial of service via kernel memory corruption and in the paranoid case may include confidentiality and integrity impact due to a kernel heap overwrite primitive. YES REQUIRES MANUAL CHECK.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 8) SKIP CVE-2026-53148 SKIP No affected files built, so skip this CVE NO - - unknown MAYBE SIMPLEFIX KPANIC INCREASED_TO_HIGH_BASED_ON_GUESSCVSS - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=8 ActionableScoreLower=7 ## 1. ActionableScore * Conservative score: 7 * Paranoid score: 8 * Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**:: ## 2. Signal breakdown * Adjacent local-bus / device peer influence: +1 A malicious Thunderbolt / USB4 XDomain peer can influence the response header and data copied by the kernel. * Memory corruption, strong corruption primitive: +2 The bug is an out-of-bounds heap write past a `kcalloc` allocation via `memcpy`. * Strong LPE plausibility: +2 Kernel heap OOB writes with peer-controlled response data are plausible privilege-escalation candidates, even if no full exploit chain is shown. * Reliable kernel crash / strong DoS: +1 Writing beyond the allocated buffer can realistically crash the kernel. * Privileged kernel/device-management memory corruption path: +1 The corruption occurs in the Thunderbolt XDomain device-management path, a highly trusted kernel subsystem. * Confidentiality impact plausible: +1 Heap corruption can plausibly affect kernel object integrity and potentially expose sensitive state in worst case. * Integrity impact plausible: +1 A heap overwrite can plausibly corrupt adjacent kernel objects. * Physical-only or rare hardware-only condition: -2 The issue is not Internet reachable. It requires access to a Thunderbolt / USB4 XDomain peer path. Paranoid score adds stronger weight to the reliability and impact of a peer-controlled kernel heap overwrite, reaching 8. ## 3. Reachability analysis The attacker does not need a local user account on the victim system, but must be able to act as a malicious Thunderbolt / USB4 XDomain peer. This is adjacent local-bus exposure, not normal network exposure. Namespaces and containers do not meaningfully affect reachability because the trigger is through device / fabric interaction rather than a local syscall interface. The path is configuration and hardware dependent, but Thunderbolt / USB4 systems are common enough that this should not be treated as a purely theoretical bug. ## 4. Severity interpretation This behaves more like an Important-class kernel memory corruption issue than an ordinary Moderate DoS. The demonstrated primitive is a kernel heap out-of-bounds write, not only a warning, NULL dereference, or resource leak. Realistic exploitation may be constrained by Thunderbolt topology, IOMMU/security policy, heap layout, and XDomain availability. However, the corruption primitive is strong enough that auto-closing as low-risk DoS would be unsafe. ## 5. One-sentence report phrase A malicious Thunderbolt XDomain peer can provide an oversized response length that causes `tb_xdp_properties_request()` to copy past a `kcalloc` buffer, resulting in kernel heap corruption with realistic DoS and plausible privilege-escalation impact. ## 6. Manual review recommendation MANUAL CHECK REQUIRED Reason: this is a peer-influenced kernel heap OOB write in a privileged device-management subsystem. Even though exposure is adjacent / local-bus rather than Internet remote, the primitive is strong enough to require manual review. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: thunderbolt: Clamp XDomain response data copy to allocation size Commit: 0b334279a82d79fb4723bd4f614305de1ab69caa Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0b334279a82d79fb4723bd4f614305de1ab69caa Commit description: tb_xdp_properties_request() derives the per-packet copy length from the response header without checking that it fits in the previously allocated data buffer. A malicious peer can set its length field larger than the declared data_length, causing memcpy to write past the kcalloc allocation. Clamp the per-packet copy length so that the cumulative offset never exceeds data_len. Fixes: cdae7c0 ("thunderbolt: Add support for XDomain properties") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-7 Signed-off-by: Michael Bommarito Signed-off-by: Mika Westerberg Signed-off-by: Greg Kroah-Hartman Changed files: drivers/thunderbolt/xdomain.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=0b334279a82d79fb4723bd4f614305de1ab69caa ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-53148 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53148 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:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H The Best / paranoid CVSS vector: AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H The Best / paranoid CVSS score: 8.8 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: 7 Paranoid ActionableScore: 8 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: IMPORTANT KPANIC detected for this report: YES Published priority for this report (same as in Subject): IMPORTANT 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).