From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-98577][MODERATE 7.0] nfc: llcp: fix WKS SAP hijacking via prefix match in nfc_llcp_wks_sap() [ Upstream Date: Sat, 24 Oct 2026 11:11:36 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-98577 X-AL-KERNEL-Priority: MODERATE 7.0 X-AL-KERNEL-Severity: MODERATE 7.0 X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: YES X-AL-KERNEL-ActionableScore: 5 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: 0c83a8a45fed256ccc5fe7160b436b671fc79fb8 List-Id: CVE: CVE-2026-98577 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: YES Patch: nfc: llcp: fix WKS SAP hijacking via prefix match in nfc_llcp_wks_sap() [ Upstream Commit: 0c83a8a45fed256ccc5fe7160b436b671fc79fb8 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0c83a8a45fed256ccc5fe7160b436b671fc79fb8 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98577 Analysis date: Sat, 24 Oct 2026 11:11:36 -0400 ActionableScore: 5 ActionableScore lower bound: unknown Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review Manual review required: YES Summary: A local NFC LLCP socket user can exploit prefix matching to claim a reserved WKS SAP and potentially impersonate or displace the legitimate service. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98577 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98577 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 7.0 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-2026-98577 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-98577 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE AEGIS_AS=1 LEGACY=MODERATE_KPANIC RESULT=DIFF (final Legacy and Aegis differ; FINAL: MODERATE_KPANIC, Aegis: 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:L/I:L/A:L';CWE-187;*CWE-20;CWE-706;BEST CVSS score: '5.3';DESCR 'A partial service name comparison in nfc_llcp_wks_sap allows a short name such as u to match a longer Well Known Service name such as urn:nfc:sn:snep. A local process able to create and bind an NFC LLCP socket may register the prefix first and obtain the reserved SAP, potentially receiving traffic intended for the legitimate service, impersonating that service, or preventing it from binding. For the CVSS the PR:L value is selected because reliable exploitation requires a local process and access to the NFC LLCP socket interface. The issue is not directly remotely triggerable by an NFC peer based on the available call context. There is no OOB access, UAF, or other memory corruption primitive. Automated impact decision path. The original SimpleNet classifier selected LOW. The primary LLM estimated paranoid CVSS 5.3 and the production ActionableScore returned 5 with recommendation Actionable Moderate / Strong Important candidate requiring manual review. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage LOW to MODERATE_KPANIC because the manual review requirement was applied. The legacy KP specialist produced a review artifact and its decision was processed by the applicable KP rules. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK. The independent weaker Aegis shadow evaluated CVSS 4.3 and ActionableScore 1 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was MODERATE. The models disagreed but the aggregation rules retained the production result. The final reported impact is MODERATE_KPANIC.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 5) MAYBE SIMPLEFIX LINUS KPANIC INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=5 PrimitiveClass=CLASS_A RealUAF=NO HostAdminRequired=NO NamespaceScopedPrivilege=UNKNOWN ImportantCandidate=YES ManualReview=REQUIRED AutoDowngradeAllowed=NO RequiresHostUID0=NO AuthorizationDecisionBypass=YES ProtectedResourceImpact=CONFIRMED B4PendingReview=NO B4PendingConfirmed=NO 1. ActionableScore * Raw base score: 5. * Conservative score: 5; no floor or cap applied. * Raw paranoid score: 5. * Paranoid score: 5; speculative disclosure or broader impersonation was not scored. * Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**:: 2. Signal breakdown * +2 concrete authorization/resource-allocation bypass: prefix comparison makes an invalid short service name resolve to a reserved Well Known Service SAP that requires an exact name. * +1 local below-host-admin trigger: supplied call-context evidence identifies a local process with NFC LLCP socket access, not host-administrator powers. * +1 integrity impact: successful binding can hijack the reserved SAP, impersonate the intended service, or prevent its legitimate registration. * +1 practical chain: short-name bind → reserved SAP assignment → interception or displacement of the legitimate WKS endpoint. * No memory-corruption, UAF, arbitrary-write, kernel-crash, LPE, or protected credential-access points. * Confidentiality was not separately scored: receiving sensitive traffic is possible, but no particular sensitive protocol exchange is established. * B4-PENDING does not apply: this is an exact-name/resource-identity validation failure, not omitted lifecycle authorization state or a capability check. 3. Reachability analysis The supported actor is a local process able to create and bind an NFC LLCP socket. The supplied summary supports below-host-admin access and does not require UID 0. It does not establish namespace-scoped capability semantics. NFC hardware or a peer may be needed to obtain useful traffic, but not necessarily to claim the SAP; no hardware penalty is justified. No race is involved—registration ordering only determines whether the attacker claims the SAP first. 4. Primitive and severity reading The primitive is unauthorized acquisition of a reserved service identifier through an inexact prefix match. It is CLASS_A authorization/resource-identity bypass, not memory corruption. The patch directly restores exact-name protection. Reserved-SAP hijacking and service displacement are supported; sensitive-data theft, host compromise, and privilege escalation remain unproven. ImportantCandidate is YES because a protected protocol identity can be allocated to an unauthorized name. Auto-downgrade is disallowed pending review of bind permissions and downstream traffic consumers. 5. One-sentence report phrase A local NFC LLCP socket user can exploit prefix matching to claim a reserved WKS SAP and potentially impersonate or displace the legitimate service. 6. Manual review advice MANUAL CHECK REQUIRED Confirm product-specific LLCP socket permissions and whether affected WKS traffic carries protected data or crosses user/service boundaries. 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: nfc: llcp: fix WKS SAP hijacking via prefix match in nfc_llcp_wks_sap() [ Upstream Commit: 0c83a8a45fed256ccc5fe7160b436b671fc79fb8 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0c83a8a45fed256ccc5fe7160b436b671fc79fb8 Changed files: net/nfc/llcp_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=0c83a8a45fed256ccc5fe7160b436b671fc79fb8 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98577 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98577 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:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L The Best / paranoid CVSS score: 5.3 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: 5 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: YES Published priority for this report (same as in Subject): MODERATE 7.0 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).