CVE-2026-43684

Executive Summary

CVE-2026-43684 is a use-after-free (UAF) memory corruption vulnerability in Apple's iOS, iPadOS, and macOS platforms, addressed through improved memory management in iOS 26.7, iPadOS 26.7, macOS Golden Gate 27, and macOS Sequoia 15.8. A local application running on an affected device can trigger the flaw to cause unexpected system termination or corrupt kernel memory. With a CVSS base score of 7.8 (High), the vulnerability poses a significant risk to enterprise fleets of Apple devices, enabling local privilege escalation and potential full kernel compromise.

Technical Analysis

CVE-2026-43684 is classified under CWE-416 (Use-After-Free), a memory safety flaw in which a program continues to reference a heap or pool allocation after that memory has been freed. In kernel contexts, this weakness is particularly severe: the freed region may be reallocated with attacker-influenced data, allowing a controlled object to be placed where a dangling pointer still references it. This class of bug is a well-established vector for kernel memory corruption and privilege escalation on hardened platforms.

The CVSS vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H is highly informative about the attack profile:

• AV:L (Local): The attacker requires local access — the vulnerability is triggered by an app executing on the target device, not via network input.
• AC:L (Low): No special conditions or race windows beyond normal execution are required to trigger the flaw.
• PR:L (Low): The attacker only needs low privileges, i.e., a standard user-level application or process.
• UI:N (None): No user interaction is required beyond the app running.
• C/I/A:H: Confidentiality, integrity, and availability impacts are all High — consistent with kernel memory corruption leading to system termination (availability) and potential code execution or data disclosure (confidentiality/integrity).

The attack surface is the local application sandbox boundary. Apple's platform security model relies on sandboxing and code signing to confine applications; a kernel UAF that is reachable from a user-space app represents a sandbox escape and a path to kernel-level compromise. Because the impact described in the NVD entry explicitly includes "corrupt kernel memory," the affected component operates at the kernel level rather than within a single user process.

Important accuracy note: The NVD description and CNA title for this CVE do not disclose the specific subsystem, function, class, or parameter involved. No function names, APIs, or file paths are provided, and none should be assumed. The technical characterization above is limited to the vulnerability class (use-after-free), the impact (kernel memory corruption / system termination), and the CVSS-derived preconditions (local, low-privilege, no UI). Specific implementation details are not available in the source data.

Exploitation Scenarios

No public proof-of-concept, exploit code, or Nuclei template is available for CVE-2026-43684. The EPSS score is 0.00195 (9.4th percentile), indicating low predicted exploitation activity in the near term. The attack chain below is therefore inferred from the vulnerability class and CVSS vector, not from observed exploit code.

1. Reconnaissance / target identification. An attacker profiles Apple devices running iOS/iPadOS versions below 26.7 or macOS versions below Sequoia 15.8 / Golden Gate 27. Any mechanism that allows delivering an application or code to the device constitutes the delivery surface: enterprise MDM distribution, malicious or trojanized App Store applications, sideloading, or a separate initial-access vector (phishing, watering hole) that drops an app. Since the vulnerability is local (AV:L), the attacker must first obtain a code-execution foothold at the user/application privilege level.

2. Triggering the use-after-free. Once a low-privileged app is executing, it invokes the vulnerable kernel-exposed operation responsible for the dangling reference. The flaw is a memory-management defect: the code frees a kernel object but continues to use the pointer. The app causes a reallocation of the freed region with controlled content (heap grooming / reallocation), converting the dangling pointer into a reference to attacker-influenced data. Because AC:L, no unusual configuration is required; the trigger occurs through normal invocation of the affected operation.

3. Payload / execution. At the vulnerability-class level, the attacker's goal is to exploit the corrupted kernel object to gain control of kernel execution or to read/write kernel memory. The precise primitive is not documented for this CVE. Successful manipulation of the freed-then-reallocated object would enable the attacker to escalate from the application sandbox to kernel privileges.

4. Post-exploitation impact. Per the NVD description, outcomes include "unexpected system termination or corrupt kernel memory." System termination yields denial of service and repeated crash/reboot loops; kernel memory corruption provides a foundation for privilege escalation, sandbox escape, and — depending on mitigations in the target build — arbitrary kernel code execution. From kernel privileges, the attacker can bypass platform security controls, persist across reboots, and access data belonging to other apps and the operating system.

Caveat: The absence of a public PoC and of specific component details means this chain is a vulnerability-class-level hypothesis. No specific function names, kernel objects, or API parameters are asserted here because none appear in the provided source data.

Impact Assessment

• Business impact: Affected devices include iPhones, iPads, and Macs running the vulnerable OS versions. In managed enterprise fleets, a kernel-level UAF reachable from a local app threatens device integrity, potentially enabling jailbreak-style compromise, security control bypass, and data exfiltration from a compromised device.
• Affected systems: iOS and iPadOS versions prior to 26.7; macOS Sequoia prior to 15.8; macOS Golden Gate prior to 27.
• Blast radius: Any device that can run a malicious or compromised application. Because exploitation is local and requires an app, the blast radius is bounded by the attacker's ability to deliver code to the device, but once achieved, kernel compromise affects the entire device, including all apps and stored data.
• CVSS subscores: Scope Unchanged (S:U) — the vulnerable component and impacted component are the same security authority (the OS kernel). Confidentiality/Integrity/Availability all High. Base 7.8 (High).
• Exploit likelihood: Low in the near term. EPSS 0.00195 (9.4th percentile); no CISA KEV listing; no public exploit code or PoC.

Detection Guidance

Because exploitation is local (AV:L) and no network signature or specific kernel artifacts are documented, the detections below target the observable consequences of a kernel use-after-free: unexpected terminations, panic/crash reports, and abnormal application behavior. They are behavioral/heuristic rather than exploitation-specific, and are provided as defensive starting points, not guaranteed indicators.

Sigma Rule

title: Potential Kernel Memory Corruption via Use-After-Free (CVE-2026-43684)
id: 8f3c2a1e-2026-4368-84aa-000000000001
status: experimental
description: Detects unexpected system termination / kernel panic events consistent with CVE-2026-43684 (use-after-free causing kernel memory corruption) on Apple platforms.
author: valtersit.com Threat Intelligence
date: 2026/01/01
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-43684
logsource:
  product: macos
  service: system
detection:
  selection_panic:
    EventID|contains:
      - 'Kernel Panic'
      - 'panic'
      - 'System Termination'
  selection_uaf_terms:
    Message|contains:
      - 'use-after-free'
      - 'freed'
      - 'corrupt'
      - 'memory'
  condition: selection_panic and selection_uaf_terms
falsepositives:
  - Legitimate kernel panics from hardware faults
  - Third-party kernel extensions with unrelated memory bugs
level: medium
tags:
  - attack.t1068
  - attack.privilege-escalation
  - cve.2026-43684

YARA Rule

rule CVE_2026_43684_Kernel_UAF_Hint
{
    meta:
        description = "Heuristic hunt rule for CVE-2026-43684 use-after-free kernel corruption artifacts on Apple platforms; no public PoC exists, indicators are behavioral"
        author = "valtersit.com Threat Intelligence"
        date = "2026-01-01"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-43684"
        cve = "CVE-2026-43684"

    strings:
        $panic = "panic" ascii wide nocase
        $uaf   = "use-after-free" ascii wide nocase
        $freed = "freed" ascii wide nocase
        $kcorr = "kernel memory" ascii wide nocase

    condition:
        (uint32(0) == 0xFEEDFACE or uint32(0) == 0xFEEDFACF or uint32(0) == 0xCEFAEDFE) and
        (($uaf and ($freed or $kcorr)) or ($panic and $kcorr))
}

Suricata IDS Rule

alert tcp any any -> any any (msg:"CVE-2026-43684 - Post-exploitation C2 after local kernel UAF (heuristic, low confidence)"; flow:established,to_server; content:"|00|"; depth:1; threshold:type limit, track by_src, seconds 60, count 1; classtype:trojan-activity; sid:202643684; rev:1; metadata:cve CVE-2026-43684;)

Note: CVE-2026-43684 is a local kernel memory-corruption flaw and has no reliable network signature. The rule above is an intentionally low-confidence placeholder targeting post-exploitation traffic; network detection is not authoritative for this vulnerability.

Elastic Detection

process where event.type == "start" and
  process.name in ("<unknown_app>") and
  process.parent.name in ("launchd", "kernel_task")

Because the affected component is the kernel and the trigger is a local app, EQL detection should focus on identifying unexpected crashes and restart loops. A preferred approach is to detect repeated system termination events:

sequence by host.id with maxspan=10m
  [ any where event.action == "system_termination" or process.name == "kernel_task" ]
  [ any where event.action == "reboot" or process.name == "kernel_task" ]

Splunk SPL Query

index=os OR index=main (sourcetype=macos_system OR sourcetype=osx_system_logs)
("kernel panic" OR "System Termination" OR "memory corruption" OR "use-after-free")
| stats count min(_time) as first_seen max(_time) as last_seen by host
| where count > 1
| eval first_seen=strftime(first_seen,"%Y-%m-%d %H:%M:%S"), last_seen=strftime(last_seen,"%Y-%m-%d %H:%M:%S")
| sort - count

Wazuh OSSEC Rule

<group name="apple,cve-2026-43684,">
  <rule id="100684" level="10">
    <if_sid>52500</if_sid>
    <match>kernel panic|System Termination|use-after-free|memory corruption</match>
    <description>CVE-2026-43684: Possible kernel memory corruption / unexpected system termination on Apple device</description>
    <mitre>
      <id>T1068</id>
    </mitre>
    <group>privilege_escalation,kernel_corruption,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 2/4 (CLAIMED — single source claims patch, not independently confirmed). The fix is stated in the NVD description as included in iOS 26.7, iPadOS 26.7, macOS Golden Gate 27, and macOS Sequoia 15.8. No vendor advisory URL, CVE-to-component mapping, or researcher credit is available in the provided data. Treat version availability as claimed and verify against Apple's official security advisories before relying on it.

1. Immediate mitigations

   • Reduce local code-execution exposure: enforce strict application vetting, block sideloading/unsigned apps via MDM, and restrict app installation to trusted sources.
   • Harden against phishing/watering-hole delivery that precedes the local trigger (email filtering, web proxy, user awareness).
   • Monitor for and investigate repeated unexpected system terminations or kernel panics across the fleet, as these are the primary observable effect of the flaw.
   • Where feasible, limit the data available to low-privilege apps to reduce post-exploitation value.

2. Patch / upgrade steps

   • Upgrade iOS/iPadOS to 26.7 or later; macOS Sequoia to 15.8 or later; macOS Golden Gate to 27 or later.
   • Verify the patch against the official Apple security release notes for the version(s) cited (NVD is the only source in the provided dataset).
   • Prioritize updates on high-value or executive devices and any device permitted to install third-party apps.

3. Long-term hardening

   • Maintain a rapid OS-update cadence for Apple endpoints via MDM, with enforcement deadlines.
   • Deploy and tune endpoint telemetry for kernel panic/crash reporting and correlate with anomalous app behavior.
   • Adopt least-privilege app provisioning and ongoing application allow-listing.
   • Track CISA KEV and EPSS for this CVE in case exploitation activity or PoC publication changes the risk picture.

References

1. NVD — CVE-2026-43684: https://nvd.nist.gov/vuln/detail/CVE-2026-43684
2. Apple Security Releases (verify iOS/iPadOS 26.7 and macOS 15.8/27 advisories): https://support.apple.com/en-us/HT201222
3. MITRE ATT&CK T1068 — Exploitation for Privilege Escalation: https://attack.mitre.org/techniques/T1068/
4. CWE-416 — Use After Free: https://cwe.mitre.org/data/definitions/416.html
5. CISA Known Exploited Vulnerabilities Catalog (check for future additions): https://www.cisa.gov/known-exploited-vulnerabilities-catalog

Threat actor / exploitation status: No threat actor campaigns are associated with this CVE in the provided data. It is not listed in CISA KEV. No public PoC or exploit code is known. EPSS is 0.00195 (9.4th percentile), indicating a low near-term exploitation likelihood as of the data snapshot.