CVE-2026-84576

Executive Summary

CVE-2026-84576 is a local information-disclosure vulnerability in Apple macOS, classified under CWE-200, where "an app may be able to access sensitive user data" that should be protected by the operating system's privacy controls. The flaw was addressed through "improved checks" in macOS Sequoia 15.8, macOS Tahoe 26.7, and macOS Golden Gate 27, indicating a failure in an enforcement or validation routine that governs app access to protected user data. With a CVSS base score of 5.5 (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N), the vulnerability grants high confidentiality impact but requires local execution with low privileges and no user interaction. No public proof-of-concept, exploit code, or KEV listing currently exists, and the EPSS score is negligible (0.00124) — indicating no observed exploitation in the wild to date, though the absence of a published PoC does not reduce the importance of patching, as Apple platform privacy bypasses are frequently weaponized by commodity macOS stealers.

Technical Analysis

CVE-2026-84576 is an exposure-of-sensitive-information vulnerability (CWE-200) affecting Apple macOS. Per the NVD description, the issue was "addressed with improved checks," which is a standard Apple phrasing indicating that a validation routine — most plausibly inside a system service that arbitrates access to user data on behalf of third-party apps — failed to correctly confirm the caller's entitlement or authorization. The fix therefore strengthens those checks rather than introducing a new capability.

The CVSS vector provides the only reliable technical constraints available:

• AV:L (Local) — the attacker must already be running code on the target host; this is not remotely reachable over the network. This is consistent with the attack surface being a local IPC boundary (e.g., a daemon or agent that mediated app requests for protected data) rather than a network service.
• PR:L (Low privileges) — the attacker does not need root. A normal, sandboxed user-level app can trigger the flaw. This is the hallmark of a macOS privacy bypass (TCC-style enforcement) rather than a kernel privilege-escalation issue.
• UI:N (No user interaction) — the malicious or compromised app does not need to prompt the victim to approve access; the checks that would normally gate consent or entitlement validation are the ones that were bypassed.
• C:H (High confidentiality) — the impact is a meaningful disclosure of sensitive user data. Apple's uniform description for these cases ("sensitive user data") typically encompasses personal data categories such as location, contacts, calendars, messages, photos, or authentication/credential material, depending on which subsystem the deficient check protected.
• I:N / A:N — no integrity or availability impact; the flaw is read-only in effect.

Because the NVD description is deliberately spartan, and no CNA title, function names, endpoints, or file paths are provided, the precise subsystem, mechanism of the failed check, and the exact data classes reachable cannot be derived from the available data. It is not accurate to assert which privacy domain or entitlement was involved. What can be stated with confidence is the class of defect: a missing or insufficient authorization check on a local, app-facing interface that allowed a low-privileged process to read user data it should not have been able to access.

The attack surface is therefore best described as the inter-process boundary between an untrusted (or compromised) user application and a privileged macOS service or framework that holds or brokers access to protected user data. Exploitation requires the attacker to already occupy the low-privilege local execution position — typically achieved through a separate initial access vector (malicious app, trojanized installer, supply-chain compromise of a legitimate app, or drive-by download).

Exploitation Scenarios

The following attack chain is inferred strictly at the vulnerability-class level. No public PoC or exploit code exists, and specific function names, endpoints, or parameters cannot be inferred from the provided data. Where the NVD description is silent, this section describes the class of behavior rather than fabricating implementation detail.

1. Reconnaissance / target identification. The attacker's objective is a macOS endpoint running an unpatched build — i.e., a version older than macOS Sequoia 15.8, macOS Tahoe 26.7, or macOS Golden Gate 27. Because the flaw is local and yields no remote banner or service fingerprint, the only meaningful identification step is host-level version enumeration (e.g., sw_vers after initial access, or fleet-management/DEP inventory data). There is no Shodan or network-scan reconnaissance surface for this CVE.

2. Triggering the specific flaw class. The attacker executes a user-level application on the target. That application then invokes a local, app-facing interface that is supposed to enforce authorization before returning sensitive user data — the check that Apple later "improved." The trigger is simply an ordinary call through that interface; because the enforcement routine is deficient, the caller's entitlement/authorization is not properly validated and the call is answered with the protected data instead of being denied. No user approval prompt appears (consistent with UI:N). The exact trigger mechanism (which subsystem, which interface, and what the check failed to verify) is not disclosed and should not be assumed.

3. Payload / execution method. At the vulnerability-class level, the "payload" is a malicious or trojanized macOS application (or a compromised legitimate app) that makes the offending local calls. The exploitation method is the request itself — there is no memory-corruption primitive, no code-injection requirement, and no elevation step implied by the CVSS vector. The low PR:L requirement means the app can operate as an ordinary, unprivileged, sandboxed user application. Whether distribution is via a signed/notarized app, an enterprise-sideloaded bundle, or a social-engineering lure is outside the scope of the CVE data; macOS Gatekeeper/notarization remain the relevant initial-access control.

4. Post-exploitation impact. The result is unauthorized read access to sensitive user data (confidentiality-only, C:H). Depending on the protected subsystem involved — which is not specified — the data could be leveraged for follow-on abuse such as credential or session theft, lateral movement to cloud accounts, or extortion. There is no integrity or availability impact; the vulnerability does not, per the CVSS vector, allow data modification, code execution as a more privileged principal, or denial of service.

Important caveat: Apple's boilerplate phrasing "sensitive user data" is reused across many unrelated privacy fixes; without the CNA title or the Apple security advisory text (neither supplied), any assertion about which data classes are reachable — location, contacts, photos, keychain, etc. — would be speculation and is deliberately not made here.

Impact Assessment

Business impact is concentrated on confidentiality of user data on managed Mac fleets. For enterprises, the relevant exposure is not a remote-code-execution worm but the incremental risk that any app running on an unpatched Mac can read data it is not entitled to. In regulated environments (finance, healthcare, defense, legal), unauthorized access to user data can carry contractual, privacy-law (GDPR/CCPA), and notification obligations even without evidence of malware. The CVSS subscores quantify this:

• Confidentiality: High — the direct effect is unauthorized disclosure of sensitive data.
• Integrity/Availability: None — no modification or disruption.
• Attack Vector: Local, Privileges Required: Low, User Interaction: None — lowers the barrier to post-access exploitation and is attractive to credential- and data-stealing macOS malware that already has a user-level foothold.

Blast radius is per-endpoint, not network-wide: exploitation is contained to the local host and does not propagate. However, because the vector only requires low local privileges, any compromised app on an unpatched Mac becomes a potential data-access primitive, and attackers who already landed (via phishing, trojanized installers, or a paired vulnerability used for initial access) gain a cheap data-collection capability. Affected systems: macOS endpoints below Sequoia 15.8, Tahoe 26.7, and Golden Gate 27; servers and non-Mac platforms are unaffected. EPSS is 0.00124 (2.4th percentile), and there is no CISA KEV listing, no public PoC, no exploit code, and no Nuclei template, so current in-the-wild exploitation is unsupported and unlikely to be observed imminently. The risk is best characterized as moderate, elevated by the severity of the data class (unknown) and by the value macOS endpoints represent as credential stores.

Detection Guidance

Detection strategy note: Because this is a local, read-only data-exposure issue with no disclosed function names, endpoints, or network traffic, the detection rules below focus on (a) the primary control signal — unpatched host version and suspicious app behavior — and (b) process/data-access heuristics. Network-layer signatures (Suricata) are inherently weak for a local-only bug; the provided rule targets only the eventuality of exfiltration of the stolen data and is explicitly a best-effort heuristic, not a CVE-specific signature.

Sigma Rule

title: macOS Endpoint Running Version Vulnerable to CVE-2026-84576
id: 7f3c1a2e-8457-4c9b-9d10-2026cve84576
status: experimental
description: Detects macOS hosts below the versions that fix CVE-2026-84576 (an app may access sensitive user data). Used for patch-status triage; not an exploitation signature.
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-84576
author: valtersit.com Threat Intelligence
date: 2026/01/01
logsource:
  product: macos
  category: process_creation
detection:
  selection_swvers:
    Image|endswith: '/sw_vers'
  selection_output_suspicious:
    # Correlate with inventory data indicating pre-fix builds.
    CommandLine|contains:
      - '15.7'
      - '26.6'
  condition: selection_swvers and selection_output_suspicious
falsepositives:
  - Administrative inventory scripts on hosts pending upgrade
level: low
tags:
  - attack.t1005
  - cve.2026.84576

YARA Rule

rule CVE_2026_84576_MacOS_Privacy_Accessor
{
    meta:
        author      = "valtersit.com Threat Intelligence"
        description = "Heuristic: identifies macOS Mach-O binaries that directly reference sensitive user-data stores, consistent with the local privacy-bypass class of CVE-2026-84576. Not an exact exploit signature."
        reference   = "https://nvd.nist.gov/vuln/detail/CVE-2026-84576"
        date        = "2026-01-01"
        tlp         = "WHITE"
    strings:
        $macho64 = { CF FA ED FE }
        $macho32 = { CE FA ED FE }
        $s1 = "TCC.db" ascii nocase
        $s2 = "kTCCService" ascii nocase
        $s3 = "/Library/Application Support/com.apple.TCC" ascii nocase
        $s4 = "NSPersonalData" ascii nocase
    condition:
        ($macho64 at 0 or $macho32 at 0) and 2 of ($s1, $s2, $s3, $s4)
}

Suricata IDS Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"POSSIBLE macOS Sensitive Data Exfiltration - CVE-2026-84576 Context"; flow:established,to_server; http.method; content:"POST"; http.header; content:"Content-Type: application/octet-stream"; dsize:>100000; threshold:type both, track by_src, count 5, seconds 300; classtype:trojan-activity; sid:202684576; rev:1; metadata:cve CVE-2026-84576; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-84576;)

Note: This rule is a generic outbound large-POST heuristic for macOS-originated exfiltration. CVE-2026-84576 is a local-only vulnerability and produces no CVE-specific network traffic; no reliable Suricata signature can be written from the available data.

Elastic Detection

process where host.os.type == "macos" and
  event.type == "start" and
  process.name in ("curl", "nc", "ncat", "base64", "osascript") and
  process.args : ("*Library/Application Support/com.apple.TCC*",
                  "*TCC.db*", "*.plist*", "*Activation*") and
  not process.parent.name in ("mdworker", "mds", "fseventsd")

This EQL targets post-access staging behavior (an app or helper reading privacy-store locations and then invoking outbound tools) rather than the vulnerability trigger itself, which is not observable at this layer.

Splunk SPL Query

index=macos_edr OR index=osquery
| eval vuln=if(match(host_version,"(15\.[0-7]|26\.[0-6])"),"vulnerable","check")
| where vuln="vulnerable"
| stats count by host, host_version, user
| sort - count

Because exploitation produces no distinctive log event, the highest-fidelity Splunk use case is patch-state visibility: enumerate macOS hosts still below Sequoia 15.8 / Tahoe 26.7 / Golden Gate 27 and drive them to remediation. A companion search for anomalous app data access can correlate process behavior:

index=macos_edr EventType=FileAccess
| search file_path="*com.apple.TCC*" OR file_path="*Keychains*"
| stats dc(file_path) as distinct_protected_files, values(process_name) as processes by host, process_name
| where distinct_protected_files > 5

Wazuh OSSEC Rule

<group name="macos,cve-2026-84576,">
  <rule id="100576" level="4">
    <decoded_as>json</decoded_as>
    <field name="host.os.name">macOS</field>
    <field name="host.os.version">15\.[0-7]|26\.[0-6]</field>
    <description>CVE-2026-84576: macOS host running version vulnerable to local sensitive-data access; remediation required.</description>
    <mitre>
      <id>T1005</id>
    </mitre>
    <group>vulnerability_detector,</group>
  </rule>

  <rule id="100577" level="10">
    <decoded_as>json</decoded_as>
    <field name="host.os.name">macOS</field>
    <field name="process.name">\.(curl|nc|osascript)$</field>
    <field name="process.args">Library/Application Support/com.apple.TCC</field>
    <description>Possible post-exploitation exfiltration of macOS privacy-store data (CVE-2026-84576 context).</description>
    <mitre>
      <id>T1041</id>
    </mitre>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 2/4 — CLAIMED. A single source (NVD) states the issue is fixed in macOS Sequoia 15.8, macOS Tahoe 26.7, and macOS Golden Gate 27. No independent vendor advisory URL, CVE entry, or Apple HT-number was supplied in the source data, and the vulnerable version floor and any Apple advisory text remain unpublished in this dataset. Treat the fix versions as credible but unconfirmed until Apple's security release notes can be verified.

1. Immediate mitigations (pre-patch / while validating):

   • Enumerate macOS inventory and flag all endpoints below the three fixed versions; prioritize devices with high-value credential or data exposure (executives, finance, developers holding cloud keys).
   • Reduce the attack surface: enforce Apple's app security stack — Gatekeeper, notarization requirement, and (where feasible) tighter MDM application allow-listing — to make it harder for a malicious app to obtain the low-privilege local foothold this flaw requires.
   • Restrict local admin and limit unmanaged app installs; monitor EDR for unusual reads of privacy-store locations and for helper/tooling processes spawned by apps.
   • Because exploitation is local-only, network segmentation and perimeter rules offer no direct protection; the effective control is endpoint hygiene and reducing the population of untrusted apps.

2. Patch / upgrade steps:

   • Upgrade affected systems to macOS Sequoia 15.8, macOS Tahoe 26.7, or macOS Golden Gate 27 (as applicable to the hardware/OS branch) via Software Update or MDM-enforced deferral/install.
   • Verify Apple's "About This Mac" / sw_vers build confirms the fixed version after upgrade.
   • Confirm remediation with a follow-up inventory sweep; do not rely on a single push in fleets where users can defer updates.

3. Long-term hardening:

   • Maintain continuous macOS version and patch compliance reporting (see the Splunk/Wazuh rules) so privacy-fix CVEs are actioned within standard SLA.
   • Apply least-privilege for local users and enforce MDM so unvetted or un-notarized applications cannot execute routinely.
   • Monitor for the broader macOS data-stealer trend that abuses privacy-control weaknesses; alert on anomalous access to protected user-data stores and subsequent outbound transfer.

References

• NVD — CVE-2026-84576: https://nvd.nist.gov/vuln/detail/CVE-2026-84576
• CWE-200 — Exposure of Sensitive Information to an Unauthorized Actor: https://cwe.mitre.org/data/definitions/200.html
• FIRST EPSS — CVE-2026-84576 score lookup: https://api.first.org/data/v1/epss?cve=CVE-2026-84576
• Apple Security Releases (verify the applicable macOS 15.8 / 26.7 / 27 advisory): https://support.apple.com/en-us/100100
• CISA Known Exploited Vulnerabilities Catalog (CVE-2026-84576 not listed as of report date): https://www.cisa.gov/known-exploited-vulnerabilities-catalog

Threat actor / exploitation evidence: None available. EPSS 0.00124 (2.4th percentile), no CISA KEV entry, no public PoC, no exploit code, and no Nuclei template. No threat-actor campaign attribution can be supported from the provided data.