From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-72003][IMPORTANT] wifi: brcmfmac: cyw: fix heap overflow on a short auth frame Date: Sat, 15 Aug 2026 03:02:11 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-72003 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: 9 X-AL-KERNEL-ActionableScore-Lower: 7 X-AL-KERNEL-Commit: 55b26abb1fa1ec406b3ad11b43c49c7624257565 List-Id: CVE: CVE-2026-72003 Priority: IMPORTANT AL-KERNEL base severity: IMPORTANT KPANIC flag: YES Patch: wifi: brcmfmac: cyw: fix heap overflow on a short auth frame Commit: 55b26abb1fa1ec406b3ad11b43c49c7624257565 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=55b26abb1fa1ec406b3ad11b43c49c7624257565 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72003 Analysis date: Sat, 15 Aug 2026 03:02:11 -0400 ActionableScore: 9 ActionableScore lower bound: 7 Actionable bucket: Strong Important candidate / Actionable Moderate at minimum Manual review required: YES Summary: A malicious AP can send a short external SAE authentication frame that causes unsigned length underflow in brcmfmac cyw and triggers an adjacent-network kernel heap overflow, leading to DoS and possible kernel memory corruption. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-72003 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72003 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-2026-72003 IMPORTANT CHECK WITH IMPACT FROM ORIG NN MODERATE 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-122;*CWE-787;CWE-191;*CWE-20;BEST CVSS score: '8.8';DESCR 'A heap overflow in brcmfmac cyw external SAE authentication handling can occur because brcmf_notify_auth_frame_rx() subtracts the IEEE 802.11 management header offset from a too small unsigned frame length. A malicious or malfunctioning AP can provide a short auth frame so the subtraction wraps to a very large copy length and memcpy writes past the allocated management frame buffer. For the CVSS the PR:N is selected because the attacker does not need privileges on the victim system and only needs the ability to interact with the victim over the adjacent Wi-Fi link. The issue is adjacent network reachable rather than Internet reachable because exploitation requires radio proximity or control of an AP used by the station. Impact can include kernel memory corruption, denial of service, and potentially privilege escalation or code execution in the kernel due to the heap overflow primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 9) YES REMOTE SIMPLEFIX NETWORK KPANIC KPANIC INCREASED_TO_HIGH_BASED_ON_GUESSCVSS YES NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=9 ActionableScoreLower=7 ## 1. ActionableScore * Conservative score: 7 * Paranoid score: 9 * Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**:: ## 2. Signal breakdown Conservative signals: * Remote reachable / network-triggerable: +2. A malicious AP can trigger the vulnerable path over Wi-Fi during external SAE authentication. This is adjacent-network reachable, not Internet-routable. * Memory corruption, strong corruption primitive: +2. The unsigned subtraction can wrap and cause memcpy() to write far past a kzalloc() buffer. * Weak LPE concern: +1. Kernel heap overflow makes privilege escalation plausible, but the patch does not demonstrate target selection, reclaim control, or a reliable overwrite target. * Reliable kernel crash / strong DoS: +1. A large out-of-bounds memcpy in kernel heap is a realistic crash vector. * Privileged kernel/device-management memory corruption path: +1. The corruption is in a trusted wireless driver path fed by firmware/AP-originated management frame data. * Confidentiality impact plausible: +1. Kernel heap corruption can plausibly lead to disclosure in worst practical analysis. * Integrity impact plausible: +1. Kernel heap overwrite can plausibly corrupt kernel state. * Corruption primitive constrained or payload/target not fully controlled: -1. The oversized copy source is derived from the received/firmware event buffer and surrounding memory, not clearly an arbitrary attacker-chosen payload. * Specific hardware/protocol mode dependency: -1. Requires affected brcmfmac/cyw hardware and the external SAE authentication path. Paranoid adjustment: * Privilege escalation plausibility upgraded from weak +1 to strong +2 because this is a remotely influenced kernel heap OOB write primitive. * The specific-mode penalty is dropped in the paranoid score because Wi-Fi client authentication paths are realistic on affected devices. ## 3. Reachability analysis The attacker does not need local code execution or credentials on the victim. The realistic attacker is a malicious or malfunctioning AP, or an attacker able to influence the AP/authentication exchange within Wi-Fi range. This is best treated as adjacent-network reachable rather than AV:N Internet reachable. Containers and namespaces are not relevant because triggering is external to the local userspace privilege model. The path is hardware and driver dependent, and requires the affected brcmfmac cyw external SAE authentication support to be in use. Call-site confidence: high. The patch and commit directly show the vulnerable length arithmetic and the memcpy() sink. ## 4. Severity interpretation This is not an ordinary Moderate DoS-only bug. The demonstrated primitive is a kernel heap overflow caused by unsigned length underflow before memcpy(). Realistic exploitation may be constrained by firmware behavior, heap layout, and kernel hardening, but the bug class and adjacent remote trigger justify Important-level manual handling. The conservative interpretation is Strong Important candidate. The paranoid interpretation reaches high-end Important because kernel heap OOB write can potentially support privilege escalation or code execution if the overwrite becomes controllable. ## 5. One-sentence report phrase A malicious AP can send a short external SAE authentication frame that causes unsigned length underflow in brcmfmac cyw and triggers an adjacent-network kernel heap overflow, leading to DoS and possible kernel memory corruption. ## 6. Manual review recommendation MANUAL CHECK REQUIRED Reason: the patch fixes a remotely influenced kernel heap overflow in a wireless driver path, with plausible confidentiality, integrity, and availability impact beyond a simple crash. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: wifi: brcmfmac: cyw: fix heap overflow on a short auth frame Commit: 55b26abb1fa1ec406b3ad11b43c49c7624257565 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=55b26abb1fa1ec406b3ad11b43c49c7624257565 Commit description: brcmf_notify_auth_frame_rx() takes the frame length from the firmware event and copies the frame body with the management header offset subtracted: u32 mgmt_frame_len = e->datalen - sizeof(struct brcmf_rx_mgmt_data); ... memcpy(&mgmt_frame->u, frame, mgmt_frame_len - offsetof(struct ieee80211_mgmt, u)); The only length check is e->datalen >= sizeof(*rxframe), so mgmt_frame_len can be anything from 0 up. offsetof(struct ieee80211_mgmt, u) is 24. When mgmt_frame_len is below that, the subtraction wraps as an unsigned value to a huge length. The memcpy then runs far past the kzalloc'd buffer. A malicious or malfunctioning AP can make the frame short during the external SAE auth exchange, so this is a remotely triggered heap overflow. Reject frames shorter than the management header offset before the copy. Fixes: 66f9093 ("wifi: brcmfmac: cyw: support external SAE authentication in station mode") Link: https://lore.kernel.org/r/178214417708.2368577.16740907093694208834@maoyixie.com Cc: stable@vger.kernel.org Co-developed-by: Kaixuan Li Signed-off-by: Kaixuan Li Signed-off-by: Maoyi Xie Acked-by: Arend van Spriel Link: https://patch.msgid.link/20260627131313.3878893-1-maoyixie.tju@gmail.com Signed-off-by: Johannes Berg Signed-off-by: Greg Kroah-Hartman Changed files: drivers/net/wireless/broadcom/brcm80211/brcmfmac/cyw/core.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=55b26abb1fa1ec406b3ad11b43c49c7624257565 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-72003 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72003 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: Not available 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: 9 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).