CVE-2026-65408

Executive Summary

CVE-2026-65408 is an integer overflow vulnerability in an unspecified Apple operating system component, addressed by improved input validation in a coordinated set of OS updates spanning iOS/iPadOS 26.7 and 27, macOS Golden Gate 27, macOS Sequoia 15.8, and macOS Tahoe 26.7. The flaw allows an attacker-supplied application to cause unexpected system termination on affected devices. Impact is availability-focused (denial of service / kernel or system crash), with no evidence in the available data of memory-corruption-based code execution, privilege escalation, or in-the-wild exploitation, and no public proof-of-concept currently exists.

Technical Analysis

The NVD description states only that "an integer overflow was addressed with improved input validation" and that "an app may be able to cause unexpected system termination." No component name, function name, file path, or API parameter is disclosed. Consequently, technical analysis must remain at the class level.

Vulnerability class — integer overflow (CWE-190): An integer overflow occurs when an arithmetic operation (addition, multiplication, size computation, or index calculation) produces a result exceeding the representable range of its integer type. In memory-safety-sensitive contexts, the classic consequence chain is:

1. A size, count, index, or length value is computed from attacker-influenced input.
2. The arithmetic wraps to a small value (or changes sign).
3. The wrapped value is subsequently used for a bounds check, buffer allocation, buffer copy, or loop bound that no longer reflects the true data volume.
4. Downstream logic either reads/writes outside intended bounds or, in the "unexpected system termination" case described here, trips a consistency check, assertion, or invalid state transition that aborts the process or panics the system.

Attack surface: The vulnerable code is reachable by an application ("an app may be able to..."), which places the flaw in the sandboxed-app reachable surface rather than the remote, pre-authentication network surface. This suggests a system-level service, framework, or inter-process interface that accepts structured input from an app process. The description does not name the subsystem, so no narrower attribution is supportable from the data provided. Because the affected products span iOS/iPadOS, macOS Sequoia, macOS Tahoe, and the newer naming line ("macOS Golden Gate," "macOS Tahoe"), the vulnerable code is shared across Apple's platform family, consistent with a common core library or kernel/daemon component present in each build.

Why "unexpected system termination": The stated outcome indicates the overflow is not (per the description) converted into controlled memory corruption leading to code execution, but rather into a failure that terminates execution — a crash, panic, or forced restart. For an enterprise fleet, "unexpected system termination" on end-user device OSes translates directly to uptime and workflow disruption rather than data compromise.

Missing data — explicitly noted: There is no CWE assignment from the source (CWE-190 above is the standard mapping for the described class), no CVSS vector supplied (N/A in the dataset), no affected-version ranges enumerated, no package metadata, and no vendor advisory text. Any statement about a specific vulnerable function, structure, or subsystem would be fabrication. The appropriate posture is detection-at-the-class-level plus patch tracking.

Exploitation Scenarios

No public PoC, exploit code, or Nuclei template is available for this CVE. The following chain is inferred at the vulnerability-class level from the NVD description and is explicitly not derived from any observed exploit.

1) Reconnaissance / target identification. An adversary targets Apple devices — iPhones, iPads, and Macs — running OS versions prior to the fixed builds listed in the description. Identification is passive: version fingerprinting via device inventory, MDM telemetry, or user-agent/OS build data. There is no network service to scan for this CVE; exposure is per-device and version-dependent.

2) Delivery of the triggering application. The flaw is app-reachable, so the realistic delivery primitive is an application the victim runs. At the class level this could be a malicious app installed from outside the curated store, a malicious app delivered via enterprise/MDM sideloading, a developer-signed test build, or a trojanized/legitimate app updated with hostile input. No specific install vector is asserted by the source data.

3) Triggering the overflow. Once executing on the victim device, the app supplies crafted input to the affected system interface. Per the vulnerability class, the crafted input drives arithmetic whose result overflows the intended numeric width, producing a value the downstream component does not expect. The specific malformed value, API, and message format are unknown and MUST NOT be guessed. What can be said is only: crafted input → integer wrap → invalid downstream state → termination.

4) Post-exploitation impact. The described result is availability loss: unexpected system termination. On macOS, "system termination" implies a full OS-level crash/restart or a daemon panic; on iOS/iPadOS it implies a crash/reset of the affected subsystem or, per Apple's terminology for severe cases, a device restart. The description does not claim memory corruption, data theft, persistence, or privilege escalation, and no such outcome should be assumed. If an enterprise app is the vector, the attacker achieves denial of service against the endpoint; repeat triggering enables sustained disruption.

Explicit caveat: Because the description provides no component name, no function names, no endpoints, and no parameters, this section deliberately omits all implementation specifics. Stating them would be fabrication.

Impact Assessment

Confidentiality: No impact indicated. The description states termination, not data exposure. Integrity: No impact indicated. Availability: High impact. "Unexpected system termination" is a direct availability loss for the affected device, potentially interrupting all local work and any dependent services. Scope: Unchanged — the effect is contained to the affected system per the described behavior.

Blast radius: Any unpatched iOS/iPadOS or macOS device in scope of the fixed versions. For an enterprise, this is the entire mobile and Mac endpoint fleet that has not yet received iOS/iPadOS 26.7/27, macOS Sequoia 15.8, macOS Tahoe 26.7, or macOS Golden Gate 27. The single-source, four-product-line fix set indicates broad, cross-platform exposure once an exploit or even a nuisance trigger becomes public.

Business impact: Primary risk is disruption — productivity loss from device resets/crashes, potential loss of unsaved work, MDM support burden, and helpdesk ticket spikes if a trigger circulates. Secondary risk is reputational/operational if a widely shared "crash app" or malformed content is weaponized for nuisance denial-of-service. CVSS score and vector were not provided by the data source (N/A); the vector supplied in METADATA is a class-based placeholder (AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H) and must be treated as advisory, not authoritative. EPSS is 0.00198 (9.8th percentile) — very low predicted exploitation likelihood at time of reporting; CVE is not in CISA KEV.

Detection Guidance

Detection must target behavior (crashes/panics, anomalous local input volume to system services) rather than known signatures, because no artifacts are published.

Sigma Rule

title: Apple OS Unexpected System Termination - Potential Integer Overflow Trigger (CVE-2026-65408)
id: 7b6c9f2e-1c4a-4d8e-9a0b-cve2026654d8e
status: experimental
description: Detects repeated unexpected system terminations / panics on Apple macOS endpoints consistent with an integer-overflow denial-of-service trigger. Correlate with recently installed or sideloaded applications at the time of crash.
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-65408
author: valtersit.com
date: 2026/07/01
logsource:
  product: macos
  service: system
detection:
  selection_crash:
    event_type:
      - 'system_termination'
      - 'kernel_panic'
      - 'userspace_crash_reporter'
    terminating_signal|contains:
      - 'SIGABRT'
      - 'SIGSEGV'
      - 'SIGBUS'
  selection_correlation:
    crash_count|gte: 3
    window: 15m
  condition: selection_crash and selection_correlation
falsepositives:
  - Hardware faults
  - Legitimate instability in beta software
level: low
tags:
  - attack.t1203
  - cve.2026.65408

YARA Rule

rule CVE_2026_65408_Apple_IntegerOverflow_Crash_Pattern
{
    meta:
        author      = "valtersit.com"
        description = "Heuristic hunting for evidence strings in crash reports referencing abrupt system termination on affected Apple builds. Class-level heuristic only; no public PoC signatures exist."
        reference   = "https://nvd.nist.gov/vuln/detail/CVE-2026-65408"
        cve         = "CVE-2026-65408"
        date        = "2026-07-01"
        tlp         = "WHITE"

    strings:
        $sig1 = "Unexpected system termination" ascii nocase
        $sig2 = "integer overflow" ascii nocase
        $sig3 = "integer overflow" wide nocase
        $sig4 = "Terminating app due to uncaught" ascii wide
        $sig5 = "panic(cpu" ascii
        $ver1 = "iOS 26.6" ascii
        $ver2 = "macOS Sequoia 15.7" ascii

    condition:
        filesize < 50MB and
        ( 2 of ($sig*) or ( 1 of ($sig*) and 1 of ($ver*) ) )
}

Note: This YARA rule is a heuristic/hunting aid derived from the advisory wording and description strings. No exploit binary or crash artifact associated with CVE-2026-65408 is publicly available, so true-positive confidence is low.

Suricata IDS Rule

alert udp $HOME_NET any -> any 5353 (msg:"CVE-2026-65408 Apple OS Anomalous Series of Termination Reports from Same Host (possible integer-overflow DoS trigger)"; flow:to_server; threshold:type threshold, track by_src, count 3, seconds 300; classtype:attempted-dos; reference:cve,CVE-2026-65408; metadata:created_at 2026_07_01, updated_at 2026_07_01; sid:900654008; rev:1;)

Applicability note: This CVE is locally triggered by an app and has no published network signature. The rule above is a generic availability-anomaly heuristic (repeated crash/telemetry reporting) and should be adapted to the environment's crash-reporting transport. It does not detect a specific protocol exploit.

Elastic Detection

sequence by host.id with maxspan=15m
  [ any where event.category == "process" and event.action == "end" and process.exit_code in ("-11", "-6", "-10", "134", "139") ]
  [ any where event.category == "process" and event.action == "end" and process.exit_code in ("-11", "-6", "-10", "134", "139") ]
  [ any where event.category == "process" and event.action == "end" and process.exit_code in ("-11", "-6", "-10", "134", "139") ]

Interpretation: three abnormal terminations of the same class on one Mac within 15 minutes is consistent with a repeatable local DoS trigger against a shared system component. Tune by enriching with the parent/installing application name.

Splunk SPL Query

index=endpoint_telemetry (source="macos_unified_log" OR source="crash_reporter")
(process="ReportCrash" OR Message="*termination*" OR Message="*panic*" OR Message="*overflow*")
| eval is_relevant=if(match(Message,"(?i)unexpected system termination|integer overflow|panic\\(cpu"),1,0)
| where is_relevant=1 OR exit_code IN (-11,-6,-10,134,139)
| stats count values(Message) as messages values(app_name) as suspects by host, user
| where count >= 3
| sort - count

Purpose: surfaces hosts experiencing clustered abnormal terminations and lists the candidate applications installed or running at the time.

Wazuh OSSEC Rule

<group name="apple,cve-2026-65408,availability,">
  <rule id="165408" level="6">
    <decoded_as>json</decoded_as>
    <field name="event_type">system_termination</field>
    <description>CVE-2026-65408: Apple endpoint reported unexpected system termination (possible integer-overflow DoS trigger).</description>
    <mitre>
      <id>T1203</id>
    </mitre>
    <group>dos,</group>
  </rule>

  <rule id="165409" level="10" frequency="3" timeframe="900">
    <if_matched_sid>165408</if_matched_sid>
    <same_field>host</same_field>
    <description>CVE-2026-65408: Repeated (3+/15m) unexpected terminations on same Apple host - likely repeatable local DoS trigger.</description>
    <mitre>
      <id>T1203</id>
    </mitre>
    <group>dos,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 2/4 — CLAIMED. A single source (NVD) states the issue is fixed in the listed OS releases; this has not been independently confirmed against a vendor advisory retrieved at the time of writing.

1) Immediate mitigations (no patch or pending confirmation):

• Restrict installation of applications from outside the curated app store using MDM configuration profiles and device supervision policies; disable or tightly scope enterprise sideloading.
• Enforce application allowlisting on managed Macs and iPhones/iPads where feasible, reducing the pool of app binaries that can reach the vulnerable interface.
• If a crash trigger begins circulating, isolate affected applications via MDM and instruct users to force-quit suspicious apps; collect crash logs centrally.
• Reduce reliance on untrusted third-party apps on high-availability endpoints (kiosks, point-of-sale, clinical devices).

2) Patch / upgrade steps:

• Upgrade to iOS 26.7 or iOS 27, iPadOS 26.7 or iPadOS 27, macOS Sequoia 15.8, macOS Tahoe 26.7, or macOS Golden Gate 27 per the NVD description.
• Validate the fix against an official Apple security advisory / support article before treating as confirmed. Verify the advertised release version numbers against Apple's published release notes; the "macOS Golden Gate 27" and "macOS Tahoe" naming should be cross-checked, as the dataset does not include the vendor advisory URL or a verified CVE-to-bulletin mapping.
• Prioritize fleets exposed to third-party app installation; standard corporate-managed iPhones/iPads/Macs are lower urgency given EPSS 0.00198 and no KEV listing, but should still be scheduled into the normal patch cycle.

3) Long-term hardening:

• Maintain authoritative device-OS asset inventory and MDM-driven minimum-version baselines; alert on devices below the fixed builds.
• Monitor Apple security releases and subscribe to NVD changes for CVE-2026-65408 to confirm patch confidence rises above 2/4.
• Enable and centrally aggregate crash/panic telemetry (macOS unified logging, ReportCrash, iOS analytics) so availability anomalies are visible.
• Adopt defense-in-depth: minimize attack surface (least-privilege app entitlements, remove unneeded apps), maintain rapid MDM-driven OS upgrade rings, and rehearse DoS event response.

References

1. NVD — CVE-2026-65408: https://nvd.nist.gov/vuln/detail/CVE-2026-65408 (primary source; single-source patch claim)
2. Apple Security Releases (vendor advisory hub): https://support.apple.com/en-us/HT201222 — consult for the specific CVE-to-bulletin mapping and to confirm fixed versions.
3. MITRE ATT&CK — T1203 Exploitation for Client Execution: https://attack.mitre.org/techniques/T1203/
4. CWE-190 — Integer Overflow or Wraparound: https://cwe.mitre.org/data/definitions/190.html
5. FIRST EPSS — CVE-2026-65408 score (0.00198, 9.8th percentile): https://api.first.org/data/v1/epss?cve=CVE-2026-65408

Exploit-in-the-wild / threat actor evidence: None available. CISA KEV listing: NO. No public PoC, no exploit code, and no Nuclei template were identified. No known threat actor campaigns are associated with this CVE in the provided data.

Report generated for valtersit.com. All technical claims are limited to the supplied NVD description; where details are absent, the analysis is explicitly bounded to the vulnerability class. Treat CVSS vector as non-authoritative (score/vector were N/A in source data).