From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-99013][MODERATE 7.0] Bluetooth: ISO: Reject concurrent BIS listener setup Date: Tue, 27 Oct 2026 02:51:37 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-99013 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: 559e4d2b6f83aaa96061659cc7104b7a0293f9ef List-Id: CVE: CVE-2026-99013 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: YES Patch: Bluetooth: ISO: Reject concurrent BIS listener setup Commit: 559e4d2b6f83aaa96061659cc7104b7a0293f9ef Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=559e4d2b6f83aaa96061659cc7104b7a0293f9ef Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99013 Analysis date: Tue, 27 Oct 2026 02:51:37 -0400 ActionableScore: 5 ActionableScore lower bound: unknown Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review Manual review required: YES Summary: Concurrent BIS listener setup leaves a stale connection-to-socket pointer that later HCI disconnect processing uses for a confirmed post-free socket reference operation. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-99013 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99013 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-2026-99013 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-99013 CHECK WITH IMPACT FROM ORIG NN IMPORTANT | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=5 LEGACY=MODERATE_KPANIC RESULT=SAME (final reconciliation agrees; DECISION: both MODERATE_KPANIC) Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H';*CWE-416;CWE-362;CWE-667;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'A race in Bluetooth ISO BIS listener setup allows two concurrent listen calls on the same bound broadcast socket to attach different connections before BT_LISTEN is published. The second attachment overwrites iso_pi sk conn, leaks the connA reference, and leaves connA sk pointing to a socket that teardown can free. A later HCI disconnect event can reach iso_conn_del and iso_sock_hold through connA, and KASAN confirms a slab use after free. For the CVSS the PR:L value reflects that an attacker needs local code execution and control of concurrent operations on the same ISO socket. AC:H reflects the race timing and Bluetooth ISO state prerequisites. Local denial of service is established, while the stale socket access and likely reference count modification make privilege escalation plausible but not proven. Automated impact decision path. The original SimpleNet classifier selected IMPORTANT. The primary LLM estimated paranoid CVSS 7 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 KP and FD specialist checks stage IMPORTANT to MODERATE_KPANIC because a specific evidence based protection or manual review veto was applied and FD false positive review allowed a downgrade. 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 produced a review artifact and its decision was processed by the applicable downgrade and preservation rules. Exact triggered rule markers were V33_ACTIVE_STATE_BOUNDARY_CANDIDATE and IMPORTANT_CANDIDATE_MANUAL_REVIEW and KP_ONLY_DOWNGRADE_VETO and DECREASED_TO_MODERATE7_BASED_ON_FALSEPOSCHECKOFDH. The independent weaker Aegis shadow evaluated CVSS 2.5 and ActionableScore 5 with primitive class CLASS_B and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. The shadow agreed with the final production impact and aggregation did not change that impact. 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 REMOTE LEAK UAF NETWORK HARDWARE LINUS KPANIC V33_ACTIVE_STATE_BOUNDARY_CANDIDATE IMPORTANT_CANDIDATE_MANUAL_REVIEW KP_ONLY_DOWNGRADE_VETO DECREASED_TO_MODERATE7_BASED_ON_FALSEPOSCHECKOFDH - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=5 PrimitiveClass=CLASS_B RealUAF=YES HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=UNKNOWN ImportantCandidate=YES ManualReview=REQUIRED AutoDowngradeAllowed=NO RequiresHostUID0=UNKNOWN AuthorizationDecisionBypass=NO ProtectedResourceImpact=NONE 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; no separate speculative exploit bonus. * Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**:: 2. Signal breakdown * +2 — Confirmed real UAF: socket teardown frees `sk` while `connA->sk` remains stale; KASAN confirms later use in `iso_sock_hold()`. * +1 — Reliable kernel crash/strong DoS is plausible from the confirmed slab UAF. * +1 — Attacker-influenced lifetime sequence: concurrent `listen()` calls overwrite `iso_pi(sk)->conn`, and subsequent socket teardown leaves the first connection stale. * +1 — Material post-lifetime operation: `iso_sock_hold()` performs a socket reference-count operation on the freed structured socket, going beyond a passive stale read. * No race penalty: concurrency is required, but the actor controls both calls and can retry; the evidence does not establish a one-shot or externally uncontrollable race. * No separate repeated-release bonus: the shown later operation is a stale reference acquisition, not a second `put`/release on the same reference. * No structured-reuse, strong-LPE, C/I, controlled-reclaim, arbitrary-write, or disclosure points: replacement contents and useful adjacent-object effects are not shown. * No extra availability point: it would duplicate the UAF crash consequence. * B4-PENDING is inapplicable because no authorization DENY-to-ALLOW change exists. 3. Reachability analysis The actor must create and bind one Bluetooth ISO broadcast socket and issue concurrent `listen()` operations on that same socket. The supplied summary labels this local PR:L, but the patch and visible call path do not establish the exact socket permission or capability checks. Therefore effective host-admin requirements and namespace-scoped privilege remain unknown, and no local-unprivileged bonus or privilege penalty is applied. No special hardware is proven necessary for establishing the race, although later HCI disconnect processing supplies the stale consumer. The actor can repeatedly attempt the concurrent setup; AC:H timing does not erase the confirmed UAF. 4. Primitive and severity reading This is an active structured-object UAF, not fixed stale storage. The second attachment overwrites the socket’s connection pointer, teardown follows `connB`, and `connA` retains a pointer to the freed socket. A later HCI disconnect reaches `iso_conn_del()` and then `iso_sock_hold()`, which operates on the stale socket reference count. This is CLASS_B: the post-free refcount operation is concrete, but controlled reclaim, refcount takeover, directed corruption, callback control, and LPE are unproven. ImportantCandidate is YES because attacker-created active state reaches a later privileged kernel consumer and the leverage of the post-free refcount mutation remains unresolved. Auto-downgrade is disallowed pending that review. 5. One-sentence report phrase Concurrent BIS listener setup leaves a stale connection-to-socket pointer that later HCI disconnect processing uses for a confirmed post-free socket reference operation. 6. Manual review advice MANUAL CHECK REQUIRED Review socket allocator reuse and `sock_hold()` behavior after reclaim, plus the exact permissions required to create and listen on the affected ISO socket. 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: Bluetooth: ISO: Reject concurrent BIS listener setup Commit: 559e4d2b6f83aaa96061659cc7104b7a0293f9ef Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=559e4d2b6f83aaa96061659cc7104b7a0293f9ef Commit description: iso_sock_listen() drops the socket lock before calling iso_listen_bis() to preserve the hdev->lock ordering. Two concurrent listen() calls on the same broadcast socket can therefore both observe BT_BOUND. Caller A can attach connA and release the locks, then caller B can acquire them and attach connB before A publishes BT_LISTEN. __iso_chan_add() checks whether connB already has a socket, but not whether the socket already has a connection. The second attachment overwrites iso_pi(sk)->conn, leaking the connA reference and leaving connA->sk intact. Socket teardown follows connB, so later events on connA can cause a stale socket access. Recheck BT_BOUND and require iso_pi(sk)->conn to be NULL after taking both the HCI device and socket locks in iso_listen_bis(). The connection check also covers the interval between attachment and publication of BT_LISTEN. Reject a competing setup with -EBADFD through the existing unlock path before allocating another connection. A recorded KASAN report from an instrumented kernel shows: BUG: KASAN: slab-use-after-free in iso_sock_hold+0x119/0x1f0 Call Trace: iso_sock_hold+0x119/0x1f0 iso_conn_del+0xe4/0x270 hci_disconn_complete_evt+0x351/0x8c0 hci_event_packet+0x71b/0xb20 hci_rx_work+0x293/0x730 Allocated by task 93: sk_prot_alloc+0x113/0x220 sk_alloc+0x2b/0x6d0 bt_sock_alloc+0x29/0x370 iso_sock_alloc.constprop.0+0x19/0x300 iso_sock_create+0x94/0x100 Freed by task 93: kfree+0x121/0x3c0 __sk_destruct+0x42b/0x540 iso_sock_release+0x29d/0x340 __sock_release+0xa1/0x260 sock_close+0x10/0x20 Fixes: 168e283 ("Bluetooth: iso: Fix circular lock in iso_listen_bis") Cc: stable@vger.kernel.org Assisted-by: GPT-6 Astra Signed-off-by: Chengfeng Ye Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Greg Kroah-Hartman Changed files: net/bluetooth/iso.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=559e4d2b6f83aaa96061659cc7104b7a0293f9ef ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-99013 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99013 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:H/PR:L/UI:N/S:U/C:L/I:L/A:H The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H The Best / paranoid CVSS score: 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: 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).