From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-93053][MODERATE REGULAR] speakup: keyhelp: guard letter_offsets possible out-of-range indexing [ Upstream Date: Thu, 17 Sep 2026 21:14:44 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-93053 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: unknown X-AL-KERNEL-Commit: fd339b9ef0accb2c24a5285df842552ebf5eb146 List-Id: CVE: CVE-2026-93053 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: speakup: keyhelp: guard letter_offsets possible out-of-range indexing [ Upstream Commit: fd339b9ef0accb2c24a5285df842552ebf5eb146 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fd339b9ef0accb2c24a5285df842552ebf5eb146 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93053 Analysis date: Thu, 17 Sep 2026 21:14:44 -0400 ActionableScore: 3 ActionableScore lower bound: unknown Actionable bucket: Borderline / manual review recommended Manual review required: YES Summary: No one-sentence report phrase was found. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-93053 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93053 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-2026-93053 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-93053 CHECK WITH IMPACT FROM ORIG NN IMPORTANT Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H';*CWE-787;CWE-129;*CWE-20;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '6.7';DESCR 'An out-of-bounds write in speakup keyhelp can occur because help_init used the first byte of each function name to compute an index into letter_offsets without validating that the name starts with a letter from a-z. If function names are changed through the speakup sysfs interface so that a name starts with another character, the computed index can underflow or exceed the letter_offsets array and corrupt adjacent kernel memory. For the CVSS the PR:H because reliable triggering requires administrative access to modify speakup function names through sysfs and typically requires local console interaction with the speakup help path. The issue is not network reachable. Impact is at least local denial of service and because this is an OOB write in kernel memory the worst case may include confidentiality or integrity impact, so it should be reviewed manually.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 3) YES WRITE OOB INIT SIMPLEFIX IMPROVEONLY LINUS LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS_AND_PRH DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=3 PrimitiveClass=CLASS_B RealUAF=NO HostAdminRequired=YES NamespaceScopedPrivilege=NO ImportantCandidate=NO ManualReview=RECOMMENDED AutoDowngradeAllowed=NO 1. ActionableScore * Raw conservative score: 1 * Conservative score: 3 * Raw paranoid score: 1 * Paranoid score: 3 * Applied conservative floor: 1 -> 3 because the patch establishes a concrete kernel out-of-bounds write, even though the supplied trigger requires host-admin-equivalent access. * Applied paranoid floor: 1 -> 3 for the same reason. * Final recommended bucket: **Borderline / manual review recommended**:: 2. Signal breakdown Positive signals: * +2 Real kernel memory corruption primitive. `help_init()` used the first byte of a function name to compute an index into `letter_offsets[]` without validating `a-z`, allowing an out-of-bounds write. * +1 Plausible kernel crash or corruption impact. The write is into kernel memory adjacent to `letter_offsets[]`, so DoS or state corruption is plausible. Negative signals: * -2 Host-admin-equivalent privilege is positively established. The supplied trigger requires root to load/configure speakup and write `/sys/accessibility/speakup/i18n/function_names`. Material non-awarded signals: * Controlled reclaim is not demonstrated. * Arbitrary write is not demonstrated. * UAF is not present. * Remote reachability is not established. * Local unprivileged trigger is not established. * Namespace-scoped privilege is not established. * C/I impact is not awarded as a separate signal because the target and payload are constrained and no protected-object modification or disclosure path is shown. * Strong LPE leverage is not awarded because the complete trigger path already requires root. 3. Reachability analysis The supplied trigger path requires root: `modprobe speakup_soft`, writing a malformed function name into the speakup sysfs interface, and then entering the help path from a TTY. This is host-admin-equivalent reachability, not ordinary local-user reachability. No evidence shows that an unprivileged user, container root, or namespace-scoped capability can perform the complete operation. There is no network vector. The vulnerable feature is also a specialized accessibility driver path, but no separate subsystem rarity penalty is needed because the host-admin requirement already captures the main practical restriction. 4. Primitive and severity interpretation The exact primitive is an out-of-bounds write to `letter_offsets[]` caused by using `(start & 31) - 1` on an unvalidated first character from a configurable function name. This is not a UAF and not a repeated release/refcount case. The object is fixed kernel storage rather than an attacker-reclaimed active object. The demonstrated class is real but constrained kernel memory corruption, so `PrimitiveClass=CLASS_B`. The demonstrated practical consequence is kernel memory corruption with possible crash. Stronger consequences such as privilege escalation are speculative here because the only established attacker is already root and no useful post-corruption primitive is shown. `ImportantCandidate=NO` because the issue is root-triggered and lacks below-host-admin reachability or demonstrated exploitation leverage. `AutoDowngradeAllowed=NO` because there is still a concrete kernel OOB write, so it should not be silently auto-closed without at least lightweight manual confirmation of the privilege boundary. 5. One-sentence report phrase A root-controlled malformed speakup function name can make `help_init()` compute an invalid `letter_offsets[]` index, causing a constrained kernel out-of-bounds write and possible local DoS. 6. Manual review recommendation MANUAL CHECK RECOMMENDED Reason: the primitive is real kernel memory corruption, but the supplied trigger requires host-admin-equivalent sysfs configuration and no unprivileged or remote path is established. 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: speakup: keyhelp: guard letter_offsets possible out-of-range indexing [ Upstream Commit: fd339b9ef0accb2c24a5285df842552ebf5eb146 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fd339b9ef0accb2c24a5285df842552ebf5eb146 Changed files: drivers/accessibility/speakup/main.c drivers/accessibility/speakup/keyhelp.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=fd339b9ef0accb2c24a5285df842552ebf5eb146 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-93053 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93053 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:L/I:L/A:H The Best / paranoid CVSS vector: AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H The Best / paranoid CVSS score: 6.7 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: unknown 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).