From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-72297][MODERATE REGULAR] net: atm: reject out-of-range traffic classes in QoS validation Date: Sun, 16 Aug 2026 00:40:32 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-72297 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: 4 X-AL-KERNEL-ActionableScore-Lower: 3 X-AL-KERNEL-Commit: 1a6dda72455b399ce9c1a12695471dc4d5c61add List-Id: CVE: CVE-2026-72297 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: net: atm: reject out-of-range traffic classes in QoS validation Commit: 1a6dda72455b399ce9c1a12695471dc4d5c61add Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1a6dda72455b399ce9c1a12695471dc4d5c61add Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72297 Analysis date: Sun, 16 Aug 2026 00:40:32 -0400 ActionableScore: 4 ActionableScore lower bound: 3 Actionable bucket: Borderline manual review recommended / Actionable Moderate candidate Manual review required: YES Summary: A local out-of-bounds read in the ATM procfs reporting path can occur because SO_ATMQOS accepts traffic_class values above ATM_ANYCLASS, allowing an invalid class index to reach pvc_info() and potentially cause information disclosure or a kernel crash. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-72297 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72297 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-2026-72297 MODERATE 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:L/UI:N/S:U/C:H/I:N/A:H';CWE-125;CWE-129;*CWE-20;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:L';BEST CVSS score: '7.1';DESCR 'An out-of-bounds read in the ATM procfs reporting path can occur because SO_ATMQOS accepts traffic_class values above ATM_ANYCLASS and stores them in vcc qos. The invalid value later reaches pvc_info(), where it is used as an index into class_name when /proc/net/atm/pvc is read. For the CVSS the PR:L is used because a local user or local process must supply the QoS value and trigger the procfs read, but full administrative privileges are not clearly required by the patch context. The issue is not directly network reachable because remote ATM traffic does not set the local SO_ATMQOS state. Impact is at least local information disclosure or denial of service. In the paranoid score, controlled out-of-bounds kernel reads may expose more sensitive memory or cause a kernel crash, so this should be reviewed manually.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline manual review recommended / Actionable Moderate candidate (with actual score 4) YES OOB SIMPLEFIX LINUS DECREASED_TO_MODERATE70_BASED_ON_ACTIONABLESCORELOWERTHAN6 DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=4 ActionableScoreLower=3 ## 1. ActionableScore * Conservative score: 3 * Paranoid score: 4 * Final recommended bucket: **Borderline manual review recommended / Actionable Moderate candidate** ## 2. Signal breakdown Triggered signals: * Local unprivileged trigger: +1 A local process can supply QoS via SO_ATMQOS and later trigger the procfs read path, assuming ATM socket access is available. * Memory corruption, weak/indirect corruption candidate: +1 The primitive is an unchecked user-influenced index into class_name[] in pvc_info(). This is an out-of-bounds read, not an OOB write. * Reliable kernel crash / strong DoS: +1 The out-of-range array access may produce an invalid pointer that is later treated as a string, plausibly causing an Oops during /proc/net/atm/pvc read. * Confidentiality impact plausible: +1, paranoid only If the out-of-bounds element resolves to a valid kernel pointer/string-like object, limited kernel memory disclosure may be possible. Subtracted signals: * Rare AND difficult-to-reach subsystem/configuration: -1 ATM is uncommon in modern deployments and the affected path requires ATM support and relevant socket/procfs usage. Not awarded: * Remote reachable: +0 Remote ATM traffic does not directly set the local SO_ATMQOS state. * Strong LPE plausibility: +0 The patch shows an OOB read, not a write primitive, UAF reclaim, type confusion, refcount abuse, or callback control. * Generic strong memory corruption: +0 No OOB write, double free, UAF reuse, heap overwrite, or arbitrary write is shown. ## 3. Reachability analysis The bug is locally reachable through the ATM QoS control path if the system has ATM support available and a local process can create or manipulate the relevant ATM socket state. The invalid traffic_class is stored after SO_ATMQOS validation succeeds and is later consumed when /proc/net/atm/pvc is read. Namespace or capability behavior is uncertain from the provided patch alone, but the conservative interpretation assumes at least a local user or local process context rather than remote reachability. The subsystem is not broadly exposed by default on most systems, which lowers practical exposure. Call-site confidence: high. The commit explicitly identifies the downstream call path from SO_ATMQOS storage to pvc_info() indexing class_name[]. ## 4. Severity interpretation This behaves more like an actionable Moderate or borderline manual-review issue than an Important-class vulnerability. The concrete primitive is a local out-of-bounds read through a procfs reporting path. Realistic impact is likely local information disclosure or kernel crash, depending on the out-of-range value and adjacent memory layout. Theoretical privilege escalation is not supported by the patch because there is no write primitive, UAF reuse, type confusion, or attacker-controlled object replacement. ## 5. One-sentence report phrase A local out-of-bounds read in the ATM procfs reporting path can occur because SO_ATMQOS accepts traffic_class values above ATM_ANYCLASS, allowing an invalid class index to reach pvc_info() and potentially cause information disclosure or a kernel crash. ## 6. Manual review recommendation MANUAL CHECK REQUIRED Reason: the bug is a user-influenced kernel out-of-bounds read with a plausible procfs disclosure or crash path, even though it is not remote and does not currently show a strong LPE primitive. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: net: atm: reject out-of-range traffic classes in QoS validation Commit: 1a6dda72455b399ce9c1a12695471dc4d5c61add Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1a6dda72455b399ce9c1a12695471dc4d5c61add Commit description: Reject ATM traffic classes above ATM_ANYCLASS in check_tp(). SO_ATMQOS stores the supplied QoS after check_qos() succeeds, so accepting larger values leaves invalid traffic_class values in vcc->qos. That bad state later reaches pvc_info(), which indexes class_name[] with vcc->qos.{rx,tp}.traffic_class. Values above ATM_ANYCLASS cause an out-of-bounds read when /proc/net/atm/pvc is read. Tighten the existing QoS validation so invalid traffic_class values are rejected at the point where user supplied QoS is accepted. Fixes: 1da177e ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Reported-by: Yuan Tan Reported-by: Xin Liu Signed-off-by: Zhengchuan Liang Signed-off-by: Ren Wei Reviewed-by: Simon Horman Link: https://patch.msgid.link/58f02c6f73d9818fd5d2022e1116759fdde6116b.1780965530.git.zcliangcn@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman Changed files: net/atm/common.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=1a6dda72455b399ce9c1a12695471dc4d5c61add ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-72297 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72297 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:L/UI:N/S:U/C:L/I:N/A:L The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H The Best / paranoid CVSS score: 7.1 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: 3 Paranoid ActionableScore: 4 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).