CVE-2026-84569

Executive Summary

CVE-2026-84569 is a sandbox access-control flaw in Apple macOS affecting the system pasteboards. An application running on the host can bypass intended sandbox restrictions and read sensitive user data contained on the shared pasteboard. Users on macOS versions prior to Golden Gate 27 — particularly those routinely running untrusted or lower-privileged apps — are affected. Impact is limited to confidentiality (CVSS 5.5, C:H/I:N/A:N) with no integrity or availability impact, but the leaked data may include credentials, tokens, or personal information copied to the clipboard.

Technical Analysis

The vulnerability is classified as CWE-862 — Missing Authorization, which in this context manifests as insufficient sandbox restrictions applied to the system pasteboards. macOS implements a cooperative pasteboard architecture in which applications interact with shared pasteboard objects (e.g., the general pasteboard) through a brokered service. The operating system sandbox is expected to mediate access so that a confined app cannot freely read pasteboard contents belonging to other applications or the system.

In this case, the access issue was addressed by adding "additional sandbox restrictions on the system pasteboards." This wording indicates that the sandbox policy governing pasteboard access was too permissive, allowing an application to reach pasteboard data that should have been gated behind additional authorization. Because this is an authorization/access-control defect rather than a memory-safety bug, exploitation does not require corrupting memory or chaining a second primitive — it requires only that a sandboxed app exercise the under-restricted pasteboard path.

Key technical observations strictly derivable from the available data:

• Attack surface: the macOS system pasteboard service and the sandbox policy that governs which applications may read from it.
• Root cause class: missing/insufficient authorization (CWE-862) — the sandbox failed to apply restrictions that would have blocked the access.
• Fix mechanism: additional sandbox restrictions (a policy-hardening fix), not a memory-management change.
• Confidentiality-only impact: CVSS rates C:H, I:N, A:N — a pure information disclosure.

The NVD entry does not disclose the specific API symbol, entitlement, or sandbox profile key that was changed. No function names, pasteboard API calls, or entitlement identifiers are provided in the source description, so they are not asserted here. Any claim of a specific affected API or profile key would be speculation.

Access requirements: The vector AV:L (local) / PR:L (low privileges) / UI:N (no user interaction) indicates the attacker needs local code execution under a low-privileged context (e.g., a sandboxed app the victim launches or that is otherwise executed on the host) and no interaction from the victim beyond the app running.

Exploitation Scenarios

No public proof-of-concept, exploit code, or Nuclei template is available (EPSS 0.00173, ~7.0th percentile; not in CISA KEV). The attack chain below is inferred at the vulnerability-class level from the NVD description and CVSS vector only; it does not assert undocumented implementation details.

1. Reconnaissance / target identification. The attacker identifies a macOS host running a version below Golden Gate 27. This is a local-only flaw, so the attacker typically arrives by one of two routes: (a) delivering a malicious or compromised application that runs under the macOS App Sandbox, or (b) leveraging an already-compromised low-privileged local context on the host. No network-facing service is involved.

2. Triggering the flaw class. The attacker's application performs a pasteboard access operation that the sandbox should have blocked. Because the affected sandbox restrictions are insufficient for the system pasteboards, the authorization check that would normally deny the read is absent or too weak (CWE-862). The read succeeds without any additional user interaction (UI:N).

3. Payload / execution method (class level). This is an information-disclosure primitive, not a code-execution primitive. The "payload" is simply the act of reading pasteboard contents that the app was not authorized to retrieve. No memory corruption, shellcode, or API-level specifics are documented, so none are asserted.

4. Post-exploitation impact. Data read from the system pasteboard is exfiltrated by the app (the disclosure is the outcome). Because confidentiality impact is High, the leaked content may include anything a user or another process placed on the pasteboard — potentially passwords, authentication tokens, personal data, or other sensitive material. Integrity and availability are unaffected.

The practical exploitability is bounded by the need for local execution as a sandboxed/low-privileged app, which keeps the overall CVSS at 5.5 (Medium) despite the High confidentiality rating.

Impact Assessment

• Confidentiality: High (C:H). Successful exploitation yields unauthorized read access to pasteboard data that could contain credentials or other sensitive user information.
• Integrity / Availability: None (I:N/A:N). This is a read-only disclosure.
• Scope: Unchanged (S:U) — impact is confined to the same security authority.
• Attack vector: Local (AV:L), low privileges (PR:L), no user interaction (UI:N), low complexity (AC:L). This combination reflects a reliable, low-friction attack for an already-resident local app.

Blast radius / business impact: Any enterprise fleet of macOS endpoints running versions below Golden Gate 27 is potentially in scope. Risk is concentrated on managed endpoints that permit installation or execution of third-party and sandboxed apps, and on users who copy sensitive material (credentials, tokens, PII, regulated data) to the clipboard. While the individual disclosure event is modest, clipboard contents are frequently security-relevant, and a malicious app that silently harvests the pasteboard can accumulate high-value secrets over time. The absence of public exploits and KEV listing lowers immediate urgency, but the hardening nature of the fix and the confidentiality-only profile make it a routine-prioritization item rather than an emergency.

Detection Guidance

Detection content below is constructed for the vulnerability class (unauthorized pasteboard access by a sandboxed process) and will require environment-specific tuning. Given the absence of disclosed API symbols or file paths, rules key on process behavior, sandbox-violation signals, and parent/child process context rather than a single known indicator.

Sigma Rule

title: Suspicious Pasteboard Access by Sandboxed Application (macOS)
id: 8f3c1a72-5b64-4d2e-9a01-84569cve2026
status: experimental
description: Detects sandboxed macOS processes accessing the system pasteboard in a manner consistent with CVE-2026-84569 (missing sandbox authorization on pasteboards).
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-84569
author: valtersit.com
date: 2026-01-01
logsource:
  product: macos
  category: process_creation
detection:
  selection_pasteboard:
    Image|endswith:
      - '/pboard'
      - '/pasteboard'
    ParentImage|contains:
      - '/Applications/'
      - '/private/var/folders/'
  selection_sandbox:
    CommandLine|contains:
      - 'com.apple.security.app-sandbox'
      - 'pasteboard'
  condition: selection_pasteboard or selection_sandbox
falsepositives:
  - Legitimate clipboard managers and text utilities
level: medium
tags:
  - attack.t1552
  - cve.2026.84569

YARA Rule

rule CVE_2026_84569_MacOS_Pasteboard_Access
{
    meta:
        author = "valtersit.com"
        description = "Detects indicators of macOS sandbox pasteboard access abuse (CVE-2026-84569)"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-84569"
        date = "2026-01-01"
        severity = "medium"

    strings:
        $p1 = "com.apple.security.app-sandbox" ascii wide
        $p2 = "NSPasteboard" ascii wide
        $p3 = "generalPasteboard" ascii wide
        $p4 = "com.apple.pasteboard" ascii wide

    condition:
        uint32(0) == 0xFEEDFACF or uint32(0) == 0xCAFEBABE
        and any of ($p*)
}

Note: The YARA rule targets Mach-O binaries (magic 0xFEEDFACF/0xCAFEBABE) that reference pasteboard and sandbox strings. String identifiers are generic pasteboard symbols, not CVE-specific API names, since none were disclosed.

Suricata IDS Rule

alert tcp $HOME_NET any -> $HOME_NET any (msg:"CVE-2026-84569 Possible macOS Pasteboard Data Exfiltration (local loopback)"; flow:to_server,established; content:"|50 4c 49 53 54|"; nocase; classtype:policy-violation; reference:cve,2026-84569; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-84569; sid:2026008456; rev:1;)

Caveat: This CVE is a local vulnerability with no network component. The Suricata rule above is a best-effort heuristic keyed on the macOS binary plist magic ("PLIST") being transmitted over loopback, which may correlate with pasteboard harvesting and exfiltration to a local listener. It is not a reliable detector of the local flaw itself and will require tuning.

Elastic Detection

sequence by process.entity_id with maxspan=30s
  [process where event.type == "start" and process.parent.name != null and
     process.name : ("pboard","pasteboard") and process.Ext.effective_parent.name != null]
  [file where event.action == "open" and file.path : ("/private/var/folders/*","/var/folders/*")]

Pasteboard-backed caches and temporary pasteboard data are stored in per-user temp locations; this sequence pairs a pasteboard-related process start with subsequent reads under the user's temp paths. Adjust fields to match your Elastic macOS integration schema.

Splunk SPL Query

index=macos OR index=endpoint (process_name="pboard" OR process_name="pasteboard" OR CommandLine="*pasteboard*")
| where (parent_process_path LIKE "%/Applications/%" OR parent_process_path LIKE "%/private/var/folders/%")
| stats count min(_time) as first_seen max(_time) as last_seen by host, user, process_name, parent_process_name, parent_process_path
| where count > 0
| sort - last_seen

Wazuh OSSEC Rule

<group name="macos,cve-2026-84569,">
  <rule id="845690" level="7">
    <decoded_as>json</decoded_as>
    <field name="process.name">pboard|pasteboard</field>
    <description>CVE-2026-84569: Possible unauthorized macOS pasteboard access by sandboxed process</description>
    <mitre>
      <id>T1552</id>
    </mitre>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 2/4 (CLAIMED — single source claims patch; not independently confirmed).

1. Immediate mitigations (if patched version cannot yet be deployed):

   • Restrict installation and execution of untrusted or unvetted applications under the App Sandbox; enforce application allow-listing on high-value macOS endpoints.
   • Reduce reliance on the shared clipboard for sensitive material — discourage copying passwords, tokens, or regulated data where an alternative (password manager direct-fill, hardware token) exists.
   • Review endpoint protection posture to detect and block pasteboard-harvesting behavior from low-trust apps.

2. Patch / upgrade steps:

   • Upgrade affected hosts to macOS Golden Gate 27, which NVD states contains the fix (additional sandbox restrictions on the system pasteboards).
   • Because the patch is single-source reported, verify against Apple's official security release notes for the corresponding macOS version before treating the fix as authoritative.
   • Track fleet compliance via your macOS patch-management tooling and prioritize endpoints running apps from outside approved sources.

3. Long-term hardening:

   • Maintain a current macOS baseline and enforce timely OS updates to keep sandbox policy hardening in place.
   • Apply the principle of least privilege to locally executed applications; minimize the number of sandboxed apps with broad system access.
   • Monitor for CWE-862-class access-control defects across the endpoint stack and integrate clipboard-access telemetry into SOC detection where feasible.

References

• NVD — CVE-2026-84569: https://nvd.nist.gov/vuln/detail/CVE-2026-84569
• CWE-862 (Missing Authorization): https://cwe.mitre.org/data/definitions/862.html
• Apple Security Releases portal (verify Golden Gate 27 fix): https://support.apple.com/en-us/HT201222
• MITRE ATT&CK T1552 (Unsecured Credentials): https://attack.mitre.org/techniques/T1552/
• CISA Known Exploited Vulnerabilities catalog (CVE-2026-84569 not listed as of this report): https://www.cisa.gov/known-exploited-vulnerabilities-catalog

Exploit-in-the-wild / threat actor note: No public PoC, exploit code, or Nuclei template is available; EPSS is 0.00173 (≈7.0th percentile) and the CVE is not in CISA KEV. There is no evidence of active exploitation or attributed threat actor campaigns at the time of writing. Claims about a patched state rest solely on the NVD description and should be validated against Apple's own advisory.