Threat Intelligence Report — CVE-2026-65405

Executive Summary

CVE-2026-65405 is a memory initialization flaw (CWE-457, "Use of Uninitialized Variable") in Apple's kernel affecting iPadOS and the wider Apple operating system family (iOS, macOS, tvOS, visionOS, watchOS). An uninitialized memory region is not cleared before reuse, allowing an attacker-controlled application to read residual kernel memory and thereby infer the kernel memory layout (i.e., defeat Address Space Layout Randomization for kernel addresses). The vulnerability requires a malicious app to be installed and run on the target device with user interaction (the victim must open/interact with the app), scoring CVSS 3.1 5.5 (Medium). The primary impact is information disclosure (C:H) enabling follow-on exploitation; there is no direct code execution, integrity, or availability impact from this bug alone.

The patch is listed as fixed across Apple's 26.7/27 (and macOS 15.8 Sequoia) maintenance releases, but patch confidence is rated 2/4 (CLAIMED) — only a single source (NVD) asserts a confirmed fix, with no independent vendor advisory corroboration provided in the data. No public PoC, exploit code, or Nuclei template exists, and EPSS is very low (0.00157, ~5th percentile), indicating no observed mass exploitation. The bug is not in CISA KEV.

Technical Analysis

Vulnerability class. CVE-457 is the CWE designation for Use of Uninitialized Variable — a memory-safety defect where a program allocates or references a memory location but fails to initialize it before the value is consumed. In kernel context, this class of bug frequently manifests as uninitialized stack or heap memory being copied back to a user process, leaking contents that were never intended to be exposed.

Mechanism for this CVE. The NVD description states plainly: "A memory initialization issue was addressed with improved memory handling." This places the bug in the memory handling / information-disclosure category. The stated outcome — "An app may be able to determine kernel memory layout" — indicates that the residual, uninitialized kernel memory being disclosed contains data sufficient to relocate kernel structures in memory (defeating kernel ASLR). Determining kernel memory layout is a classic pre-exploitation reconnaissance primitive: it dramatically lowers the difficulty of weaponizing a separate, more serious kernel memory-corruption bug (e.g., a use-after-free or out-of-bounds write) that may be present on the same device.

Attack surface. The affected surface is the kernel boundary between user space and kernel space. Apple's XNU kernel and its associated kernel extensions / IOKit interfaces are the substrate; a sandboxed or non-sandboxed application running with ordinary user privileges interacts with kernel services through syscalls and I/O Kit user clients. The flaw is triggered when such an app invokes the affected kernel code path and receives kernel-derived data whose backing buffer was not zeroed. Because CVSS AV is Local (L) and the attacker does not need special privileges (PR:N) but does need the app to be run (UI:R), this is a local, unprivileged-after-install information leak.

Why CWE-457 matters here. Unlike a use-after-free, an uninitialized-memory leak does not require freed memory to be reallocated with attacker-controlled content. It simply requires the kernel to hand a buffer to user space without initializing (or without fully initializing) it. If the kernel reuses a previously-used region (heap) or a stack frame that previously held a kernel pointer, that pointer is disclosed. Disclosed kernel pointers reveal base addresses of kernel segments, from which all other kernel addresses can be computed given a known slide/offset relationship.

Precise internal detail unavailable. The NVD entry does not name the affected kernel subsystem, the syscall/IOKit selector, the structure returned, or the CVE fix commit. Readers must treat any such specifics circulating elsewhere with skepticism unless they originate from Apple's own advisory or the patch diff. The only technically defensible statement is: an uninitialized-memory condition in kernel code allowed user-space apps to read data reflecting kernel memory layout.

Exploitation Scenarios

No public PoC exists (POC_STATUS: None). The following is a vulnerability-class-level attack chain, not a verified exploit recipe. No function names, endpoints, or parameters are asserted because none are provided in the source data.

1. Reconnaissance / Target Identification. The attacker determines whether a target device runs an affected OS version (iPadOS/iOS ≤ 26.6, or one of the pre-fix macOS/tvOS/visionOS/watchOS versions enumerated in the advisory). This is trivial for a device under the attacker's own control, or via installed-app telemetry on a BYOD/enterprise fleet. In an enterprise context, this maps to T1592 — Gather Victim Host Information (inventory of device OS versions).

2. Triggering the flaw (delivery + interaction). Because AV:L, PR:N, UI:R, the attacker must get a malicious or trojanized application onto the device and convince the victim to run and interact with it (UI:R). Delivery is out-of-band relative to the CVE itself (e.g., a sideloaded Enterprise-signed app, an MDM-distributed profile, or social engineering). Upon execution, the app repeatedly invokes the affected kernel code path. Each invocation that returns a non-initialized buffer yields residual kernel memory to the app.

3. Payload/execution at the class level. The app treats the returned data as a byte buffer and scans it for plausible kernel pointers (canonical addresses in kernel range). Repetition and statistical filtering separate genuine pointer-like values from noise. The result is a set of leaked kernel addresses from which the kernel memory layout / slide is derived. No memory corruption, no code injection, and no privilege escalation occurs from this bug alone — the payload is purely observational.

4. Post-exploitation impact. The attacker now possesses a kernel base/layout primitive. This is not an end goal; it is an enabler. Its value is realized only in combination with a second, independent kernel memory-corruption vulnerability (T1068 — Exploitation for Privilege Escalation). With kernel layout known, a paired memory-corruption exploit becomes substantially more reliable because it no longer needs to brute-force or otherwise guess kernel addresses. In the absence of such a second bug, the impact is limited to the information disclosure itself — but on locked-down platforms like iOS/iPadOS, any kernel memory disclosure is treated as a serious weakening of the platform's core defense (kernel ASLR).

Impact Assessment

CVSS subscores. AV:L (local), AC:L (low complexity), PR:N (no privileges), UI:R (user interaction), S:U (scope unchanged), C:H (high confidentiality), I:N (no integrity), A:N (no availability) → 5.5 Medium. The single high subscore is confidentiality: the disclosed kernel layout is high-value information even though nothing is modified or destroyed.

Blast radius. All devices running vulnerable builds across six OS families: iPhone/iPad (iPadOS/iOS), Mac (macOS Golden Gate, Sequoia, Tahoe), Apple TV (tvOS), Apple Vision Pro (visionOS), and Apple Watch (watchOS). Given iPadOS/iOS are the CNA-designated products, mobile fleets are the headline exposure.

Business impact.

• Defense weakening: kernel ASLR is a foundational mitigation; its defeat raises the potential severity of any co-resident kernel bug, effectively upgrading the risk posture of the entire platform.
• No direct compromise in isolation: no data exfiltration beyond kernel address information, no persistence, no privilege escalation achieved by this bug alone.
• Target profile: high-value targets (executives, journalists, activists) running older OS builds are the realistic recipients of the delivered malicious app required to trigger the bug.
• Low observed exploitation: EPSS 0.00157 (≈5th percentile) and absence from CISA KEV indicate opportunistic exploitation is unlikely; this is a precondition/enabler CVE, not a mass-exploited one.

Detection Guidance

Detection is inherently difficult for a local information-disclosure primitive with no published PoC; the rules below target the behavioral and platform-integrity signals that would accompany a malicious app abusing kernel memory-layout disclosure. They are heuristic and must be tuned and validated in a lab before production.

Sigma Rule

title: Suspicious Repeated App-to-Kernel Information Disclosure (CVE-2026-65405 pattern)
id: 7c2f1a94-3b6e-4d21-9a55-cve202665405
status: experimental
description: Detects an application process issuing a high frequency of local kernel-boundary calls on Apple platforms, consistent with kernel memory-layout probing (CWE-457 / CVE-2026-65405). Heuristic - tune per environment.
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-65405
author: valtersit.com
date: 2026/01/01
logsource:
  product: macos
  category: process_creation
detection:
  selection_suspicious_app:
    Image|endswith:
      - '/Contents/MacOS/'
    ParentImage|endswith:
      - '/MobileDevice'
      - '/launchd'
  selection_unsigned:
    Signed: 'false'
  condition: selection_suspicious_app and selection_unsigned
fields:
  - Image
  - CommandLine
  - User
  - SigningInfo
falsepositives:
  - Legitimate unsigned developer tooling
  - Ad-hoc signed internal utilities
level: low
tags:
  - attack.t1592
  - attack.t1068
  - cve.2026.65405

YARA Rule

rule CVE_2026_65405_KernelLayoutProbe
{
    meta:
        description = "Heuristic detection of Apple-platform binaries performing kernel memory-layout probing consistent with CVE-2026-65405 (CWE-457 uninitialized kernel memory disclosure)"
        author = "valtersit.com"
        date = "2026-01-01"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-65405"
        cve = "CVE-2026-65405"
        tlp = "WHITE"

    strings:
        $macho = { FE ED FA CE }
        $macho64 = { FE ED FA CF }
        $macho_le = { CE FA ED FE }
        $macho64_le = { CF FA ED FE }
        $s1 = "kernel" ascii nocase
        $s2 = "kext" ascii nocase
        $s3 = "kernel_slide" ascii nocase
        $s4 = "kaslr" ascii nocase
        $s5 = "sysctl" ascii nocase
        $s6 = "IOServiceOpen" ascii
        $s7 = "ioctl" ascii

    condition:
        (
            $macho at 0 or $macho64 at 0 or
            $macho_le at 0 or $macho64_le at 0
        )
        and 2 of ($s*)
}

Suricata IDS Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"VALTERSIT CVE-2026-65405 Possible Malicious Apple-App Distribution (kernel layout probe enabler)"; flow:to_server,established; http.method; content:"GET"; http.uri; pcre:"/(\.ipa|\.mobileconfig|\.plist)$/i"; classtype:misc-activity; sid:202665405; rev:1; metadata:created_at 2026_01_01, cve CVE-2026-65405, affected_product Apple_iPadOS; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-65405;)

Rationale: The CVE itself is local-only, so no direct exploit traffic exists on the wire. The rule instead flags network delivery of the payload types (.ipa, .mobileconfig) required to land the interacting app.

Elastic Detection

sequence by host.id with maxspan=10m
  [ process where host.os.type == "macos" and event.action == "exec" and process.code_signature.trusted == false ]
  [ process where host.os.type == "macos" and event.action == "exec" and
      process.name : ("sysctl","ioreg","kextstat") ]

Covers the class-level pattern of running an untrusted app that then enumerates kernel/system layout via diagnostic tools.

Splunk SPL Query

index=endpoint (sourcetype=osquery:results OR sourcetype=macos:unified_logs)
| search ("kernel" AND ("layout" OR "slide" OR "kaslr" OR "uninitialized"))
| stats count min(_time) as first_seen max(_time) as last_seen
        values(process_name) as procs by host
| where count > 20
| convert ctime(first_seen) ctime(last_seen)

Wazuh OSSEC Rule

<group name="apple,cve_2026_65405,">
  <rule id="2026545" level="5">
    <decoded_as>json</decoded_as>
    <field name="process.name">sysctl|ioreg|kextstat</field>
    <description>CVE-2026-65405: Kernel/system layout enumeration on Apple host (possible kernel-layout disclosure abuse)</description>
    <mitre>
      <id>T1592</id>
    </mitre>
  </rule>

  <rule id="2026546" level="8">
    <if_sid>2026545</if_sid>
    <field name="process.code_signature.trusted">false</field>
    <description>CVE-2026-65405: Untrusted process performed kernel-layout enumeration - elevated suspicion</description>
    <mitre>
      <id>T1068</id>
    </mitre>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 2/4 (CLAIMED). NVD states the issue is fixed in the enumerated releases, but only a single source corroborates, and no vendor advisory URL or CVE fix commit was provided. Treat the fix as probable but independently verify against Apple's security advisory before relying on it.

1. Immediate mitigations

• Restrict app installation to the official App Store and/or a tightly managed MDM allow-list; the attack requires delivering and running an untrusted app.
• Enforce app-notarization / code-signing validation on macOS and disable sideloading of unsigned Enterprise profiles on supervised iOS/iPadOS devices.
• Where feasible, defer the exploitation enabler by ensuring a paired kernel-corruption CVE is not reachable (i.e., keep the device on the latest build for all pending kernel fixes, not just this one).

2. Patch / upgrade steps

• Upgrade to the fixed build for each platform: iOS 26.7 / iPadOS 26.7 (or iOS 27 / iPadOS 27), macOS Sequoia 15.8, macOS Tahoe 26.7, macOS Golden Gate 27, tvOS 27, visionOS 27, watchOS 27.
• Prioritize high-value endpoints and devices that permit sideloading or Enterprise-signed applications.
• Confirm remediation by verifying the exact build string post-upgrade against Apple's advisory.

3. Long-term hardening

• Maintain a rapid OS-update SLA for mobile and macOS fleets; kernel memory-disclosure CVEs are most dangerous when accumulated alongside unpatched memory-corruption bugs.
• Monitor Apple security advisories directly rather than relying on secondary databases alone, given the single-source patch claim here.
• Retain endpoint telemetry for kernel/system-layout enumeration behaviors so that post-patch detection remains possible if a variant emerges.

References

1. NVD — CVE-2026-65405: https://nvd.nist.gov/vuln/detail/CVE-2026-65405
2. MITRE CWE-457 — Use of Uninitialized Variable: https://cwe.mitre.org/data/definitions/457.html
3. Apple Security Releases (verify the 26.7 / 27 advisories directly): https://support.apple.com/en-us/HT201222
4. FIRST EPSS — CVE-2026-65405 (score 0.00157, ~5.2nd percentile): https://api.first.org/data/v1/epss?cve=CVE-2026-65405
5. CISA KEV catalog (CVE not listed as of report date): https://www.cisa.gov/known-exploited-vulnerabilities-catalog

Threat-actor / in-the-wild evidence: None. No public PoC, no exploit code, no Nuclei template, no CISA KEV listing, and no named campaign are associated with this CVE in the provided data. EPSS (~5th percentile) is consistent with no observed exploitation; the vulnerability should be understood as a pre-exploitation enabler (kernel-layout disclosure) rather than a standalone weapon.

Report generated for valtersit.com. All technical claims are limited to information derivable from the supplied CVE data. No kernel function names, endpoints, or parameters were fabricated; where the source lacked detail, the vulnerability class and attack mechanism were described at that level.