From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-97453][MODERATE REGULAR] ACPICA: validate byte_count in acpi_ps_get_next_package_length() [ Upstream Date: Thu, 24 Sep 2026 18:06:31 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-97453 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: 1 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: 780f380c66b80030379bec65bb1bd09ce6f6d9fc List-Id: CVE: CVE-2026-97453 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: ACPICA: validate byte_count in acpi_ps_get_next_package_length() [ Upstream Commit: 780f380c66b80030379bec65bb1bd09ce6f6d9fc Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=780f380c66b80030379bec65bb1bd09ce6f6d9fc Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97453 Analysis date: Thu, 24 Sep 2026 18:06:31 -0400 ActionableScore: 1 ActionableScore lower bound: unknown Actionable bucket: Ordinary Moderate Manual review required: NO Summary: No one-sentence report phrase was found. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-97453 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97453 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: NO A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-97453 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-97453 CHECK WITH IMPACT FROM ORIG NN MODERATE Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:H';CWE-125;*CWE-20;CWE-1284;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.1';DESCR 'An out of bounds read in ACPICA package length parsing can occur when malformed AML declares additional PackageLength bytes beyond parser_state aml_end. The parser may read beyond the available AML buffer while decoding the package length. For the CVSS the PR:H reflects that reliable triggering normally requires control of ACPI tables or AML through firmware boot configuration or an equivalent administrative capability. The issue is not directly network reachable. Impact is primarily limited availability impact from malformed AML handling. A limited confidentiality impact and a kernel crash are conservative possibilities for the paranoid score, but the patch does not show an out of bounds write use after free or a supported privilege escalation primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1) YES DANGER SIMPLEFIX DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=1 PrimitiveClass=CLASS_C RealUAF=NO HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=UNKNOWN ImportantCandidate=NO ManualReview=RECOMMENDED AutoDowngradeAllowed=YES 1. ActionableScore * Raw conservative score: 1 * Conservative score: 1 * Raw paranoid score: 1 * Paranoid score: 1 * Final recommended bucket: **Ordinary Moderate**:: No floor or cap was applied. 2. Signal breakdown * +1 Firmware-mediated external influence. The malformed AML input is normally supplied through ACPI tables and platform firmware. This is not direct remote reachability and does not establish that an ordinary local user can provide malicious AML. * +0 Limited out of bounds read concern. The patch establishes that package-length decoding may read beyond `parser_state->aml_end` when the AML buffer has insufficient bytes. The patch does not establish an out of bounds write, use-after-free, object replacement, refcount corruption, or attacker-controlled target. * +0 Reliable kernel crash not awarded. The supplied patch validates a parser boundary but does not demonstrate a panic, Oops, or reproducible crash. * +0 Confidentiality not awarded. No path copies the bytes read past the AML boundary to userspace, network output, logs, or another attacker-visible channel. * +0 Integrity not awarded. No write primitive or security-sensitive state modification is shown. * +0 Remote reachability not awarded. AML is firmware or boot-configuration mediated input, not directly attacker-supplied network traffic. * +0 Local unprivileged trigger not awarded. The supplied evidence does not show that an ordinary local user can install or override the relevant ACPI AML table. * No host-admin penalty was applied. Host-admin-equivalent control is plausible for ACPI table override or boot configuration, but it is not positively established by the supplied patch. * No rare-hardware or race penalty was applied. The issue is malformed-input parsing, not a timing race or a hardware-specific asynchronous condition. 3. Reachability analysis The vulnerable operation parses AML PackageLength encoding in ACPICA. A malformed AML buffer can declare one to three additional PackageLength bytes when fewer bytes remain before `aml_end`, causing reads beyond the intended parser boundary. The likely input source is an ACPI table provided by platform firmware, a boot-time ACPI table override, or another privileged platform configuration mechanism. The supplied evidence does not establish a complete attacker path for an ordinary user, a container user, or a namespace-scoped capability holder. HostAdminRequired is therefore UNKNOWN rather than YES. The common requirement for firmware modification, boot configuration control, or ACPI table injection is not enough to claim a proven host-admin requirement from the patch alone. NamespaceScopedPrivilege is UNKNOWN because no namespace-aware input or capability path is shown. There is no direct network trigger, no special runtime device interface, no demonstrated prior attacker-controlled setup, and no race requirement. 4. Primitive and severity interpretation The exact primitive is a bounded parser out of bounds read. Before the fix, `acpi_ps_get_next_package_length()` reads `aml[0]` without first confirming at least one remaining byte, and can later read additional PackageLength bytes despite insufficient remaining AML data. This is not a UAF, refcount bug, double release, active-object lifetime issue, or ownership violation. It is also not an out of bounds write. The patch clamps parsing to `aml_end` and returns a zero package length when the encoded byte count is invalid. The appropriate class is CLASS_C because the established behavior is malformed parser state and a potential invalid read. The patch does not establish an independently useful memory-corruption primitive, disclosure path, privilege escalation, or security-boundary bypass. The supplied CVSS hint allows a paranoid `C:L/I:N/A:H` interpretation, but the ActionableScore does not award confidentiality or strong availability points because neither disclosure nor crash behavior is demonstrated in the supplied evidence. The realistic operational consequence is malformed AML parsing failure, with a possible but unproven crash depending on surrounding allocation and parser state. ImportantCandidate is NO. AutoDowngradeAllowed is YES because no meaningful unresolved corruption, lifetime, authorization, or ownership primitive remains after excluding speculative consequences. 5. One-sentence report phrase Malformed ACPI AML PackageLength data can cause ACPICA to read beyond the parser AML boundary, but the supplied patch establishes only a limited invalid-read parser condition without a demonstrated disclosure, write, crash, or privilege-escalation primitive. 6. Manual review recommendation MANUAL CHECK RECOMMENDED ACPICA parses firmware-mediated input in kernel context, so callers and malformed-table error handling should be checked manually, but the available patch evidence supports only a constrained out of bounds read. 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: ACPICA: validate byte_count in acpi_ps_get_next_package_length() [ Upstream Commit: 780f380c66b80030379bec65bb1bd09ce6f6d9fc Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=780f380c66b80030379bec65bb1bd09ce6f6d9fc Changed files: drivers/acpi/acpica/psargs.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=780f380c66b80030379bec65bb1bd09ce6f6d9fc ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-97453 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97453 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:N/I:N/A:L The Best / paranoid CVSS vector: AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:H The Best / paranoid CVSS score: 5.1 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: unknown 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: 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).