From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-46333][IMPORTANT] ptrace: slightly saner 'get_dumpable()' logic Date: Thu, 09 Jul 2026 16:26:54 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-46333 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: 7 X-AL-KERNEL-ActionableScore-Lower: 6 X-AL-KERNEL-Commit: 93d4ba49d18e3d7fb41a9927c2d0cca5e9dfefd6 List-Id: CVE: CVE-2026-46333 Priority: IMPORTANT AL-KERNEL base severity: IMPORTANT KPANIC flag: YES Patch: ptrace: slightly saner 'get_dumpable()' logic Commit: 93d4ba49d18e3d7fb41a9927c2d0cca5e9dfefd6 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=93d4ba49d18e3d7fb41a9927c2d0cca5e9dfefd6 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46333 Analysis date: Thu, 09 Jul 2026 16:26:54 -0400 ActionableScore: 7 ActionableScore lower bound: 6 Actionable bucket: Strong Important candidate / Actionable Moderate at minimum Manual review required: YES Summary: A ptrace dumpability logic flaw allowed reduced-capability uid 0 callers without `CAP_SYS_PTRACE` to pass access checks for tasks without an `mm`, potentially exposing protected task state or sensitive task-associated resources. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-46333 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46333 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-2026-46333 IMPORTANT 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:L/UI:N/S:U/C:H/I:N/A:N';CWE-863;CWE-284;*CWE-200;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N';BEST CVSS score: '5.5';DESCR 'ptrace_may_access could skip dumpability based restrictions for tasks without an mm, including kernel threads and tasks after exit_mm. This allowed a uid 0 caller with matching credentials but without CAP_SYS_PTRACE to pass checks that should require stronger ptrace authority. For the CVSS the PR:L is used for the paranoid score because reduced capability root, container root, or a service account with uid 0 but without CAP_SYS_PTRACE can be a realistic attacker in practical deployments. The issue is local only and is not network reachable. Impact is primarily information disclosure through ptrace protected task details, with no direct evidence of memory corruption, arbitrary write, or kernel crash.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 7) YES READ INIT IMPROVEONLY KPANIC INCREASED_TO_MODERATE70_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN5 KPANIC INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7 NO YES checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=7 ActionableScoreLower=6 ## 1. ActionableScore * Conservative score: 6 * Paranoid score: 7 * Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**:: ## 2. Signal breakdown * +2 Security-boundary bypass with practical sensitive-object access. `ptrace_may_access()` could incorrectly allow access when the target task had no `mm`, bypassing the intended dumpability and `CAP_SYS_PTRACE` boundary. * +2 Sensitive task state / file-descriptor access primitive. `ptrace_may_access()` gates sensitive procfs and pidfd-style task inspection paths, so bypassing it can expose privileged process state or potentially privileged file descriptors. * +1 Process-exit privileged resource lifetime window. The bug is specifically tied to tasks after `exit_mm()`, where `mm` disappears before all task-related protected resources are necessarily irrelevant. * +1 Confidentiality impact plausible. The realistic impact is unauthorized inspection of protected task details, not memory corruption. * +1 Practical exploit chain strongly implied, paranoid only. The Qualys context plus ptrace and dumpability semantics make a process-exit permission-bypass chain plausible enough for manual review. * 0 No memory-corruption score. The patch does not show UAF, OOB write, arbitrary write, type confusion, or refcount takeover. * 0 No full root penalty. Reduced-capability uid 0, container root, or sandboxed root without `CAP_SYS_PTRACE` is not equivalent to full host root because the bug bypasses a meaningful capability boundary. ## 3. Reachability analysis The bug is locally reachable by a caller with matching credentials, most notably uid 0 without `CAP_SYS_PTRACE`. It is not a normal unprivileged-user bug and is not network reachable. Namespace and container setups matter because reduced-capability root or service accounts running as uid 0 may be common in hardened deployments, and the intended security model relies on capabilities still restricting ptrace-like access. The affected path is broad because `ptrace_may_access()` is a central authorization helper used beyond classic ptrace. ## 4. Severity interpretation This is not a memory corruption vulnerability and should not be scored as LPE based on kernel overwrite primitives. It behaves as an access-control and confidentiality boundary bypass. Realistic impact is unauthorized access to protected task information and possibly sensitive task-associated objects through ptrace-gated interfaces. Because it affects capability-separated root models and was reported as a security issue, it should be treated as at least actionable Moderate and plausibly an Important candidate for manual triage. ## 5. One-sentence report phrase A ptrace dumpability logic flaw allowed reduced-capability uid 0 callers without `CAP_SYS_PTRACE` to pass access checks for tasks without an `mm`, potentially exposing protected task state or sensitive task-associated resources. ## 6. Manual review recommendation MANUAL CHECK REQUIRED This is a security-boundary bypass in a central authorization helper, reported by Qualys, and the practical impact depends on procfs, pidfd, task-exit timing, and reduced-capability root deployment models. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: ptrace: slightly saner 'get_dumpable()' logic Commit: 93d4ba49d18e3d7fb41a9927c2d0cca5e9dfefd6 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=93d4ba49d18e3d7fb41a9927c2d0cca5e9dfefd6 Commit description: The 'dumpability' of a task is fundamentally about the memory image of the task - the concept comes from whether it can core dump or not - and makes no sense when you don't have an associated mm. And almost all users do in fact use it only for the case where the task has a mm pointer. But we have one odd special case: ptrace_may_access() uses 'dumpable' to check various other things entirely independently of the MM (typically explicitly using flags like PTRACE_MODE_READ_FSCREDS). Including for threads that no longer have a VM (and maybe never did, like most kernel threads). It's not what this flag was designed for, but it is what it is. The ptrace code does check that the uid/gid matches, so you do have to be uid-0 to see kernel thread details, but this means that the traditional "drop capabilities" model doesn't make any difference for this all. Make it all make a *bit* more sense by saying that if you don't have a MM pointer, we'll use a cached "last dumpability" flag if the thread ever had a MM (it will be zero for kernel threads since it is never set), and require a proper CAP_SYS_PTRACE capability to override. Reported-by: Qualys Security Advisory Cc: Oleg Nesterov Cc: Kees Cook Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman Changed files: include/linux/sched.h kernel/exit.c kernel/ptrace.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=93d4ba49d18e3d7fb41a9927c2d0cca5e9dfefd6 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-46333 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46333 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:N/A:N The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N The Best / paranoid CVSS score: 5.5 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: 6 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: 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).