Threat Intelligence Report — CVE-2026-86910

Executive Summary

CVE-2026-86910 is a path-validation flaw (CWE-22) in Apple macOS that allows a local application to access restricted files by bypassing permission checks. The vulnerability affects macOS Golden Gate 27, macOS Sequoia 15.8, and macOS Tahoe 26.7 and earlier versions, with a CVSS base score of 5.5 (Medium). Successful exploitation requires user interaction and a local foothold, but yields high confidentiality impact, exposing sensitive system or user data to a malicious or compromised application.

Technical Analysis

This vulnerability is classified as CWE-22 (Improper Limitation of a Pathname to a Restricted Directory, commonly known as Path Traversal). The NVD description states: "A permissions issue was addressed with improved path validation. This issue is fixed in macOS Golden Gate 27, macOS Sequoia 15.8, macOS Tahoe 26.7. An application may be able to access restricted files."

The core flaw lies in insufficient sanitization or normalization of file paths supplied to a privileged or permission-gated file operation. When an application passes a crafted path containing directory traversal sequences (e.g., ../) or symbolic link manipulations, the system may resolve the path to a location outside the intended restricted directory. Because the permission check is applied to the pre-resolution path rather than the canonicalized target, the application can read files that should be off-limits under macOS's sandboxing, TCC (Transparency, Consent, and Control), or file-system permissions model.

The attack surface is local: any application running in the user's context can invoke the vulnerable file-access routine. The user interface interaction (UI:R) suggests that the flaw may be triggered through a file-open dialog, drag-and-drop operation, or a crafted document that an application processes. The CVSS vector AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N indicates that no privileges are required to attempt exploitation, but user interaction is needed; successful attacks compromise only confidentiality (high), with no integrity or availability impact and no scope change.

"Improved path validation" in the patch indicates that Apple added canonicalization or symlink-resolution checks before granting access to restricted paths. The exact vulnerable component (e.g., a specific framework, service, or API) is not disclosed in the available NVD data. This is typical of Apple security advisories, which often omit granular technical details to limit weaponization.

Exploitation Scenarios

No public PoC or exploit code is available for CVE-2026-86910. The attack chain below is inferred from the vulnerability class (CWE-22) and the CVSS vector.

1. Reconnaissance/Target Identification: An attacker identifies a macOS system running an affected version (Golden Gate < 27, Sequoia < 15.8, or Tahoe < 26.7). The attacker must already have a local presence—either a malicious application installed on the machine or the ability to convince the user to run a crafted application or open a malicious file.

2. Triggering the Flaw: The attacker's application constructs a file path that includes directory traversal sequences or a symbolic link pointing to a restricted file (e.g., a path that resolves to /etc/passwd, a user's protected data container, or TCC-protected directories). The application then invokes the vulnerable file-access API or operation. Because the pre-patch validation does not canonicalize the path before checking permissions, the traversal escapes the intended restricted scope.

3. Payload/Execution Method: At the vulnerability-class level, the payload is a crafted path string. No specific function names, endpoints, or parameters are disclosed in the NVD description; therefore the exact invocation method (e.g., which API or service) cannot be determined from available data. The attacker's application simply requests access to a file outside its sandbox using the traversed path.

4. Post-Exploitation Impact: Successful exploitation allows the malicious application to read restricted files, which may include configuration files, credentials, tokens, or personal data. This breach of confidentiality can enable further attacks such as lateral movement, credential theft, or data exfiltration. There is no integrity or availability impact, and the scope remains unchanged.

The requirement for user interaction (UI:R) likely means the attacker must convince the user to open a file or grant an initial action, but once that occurs, the path traversal bypasses subsequent permission checks.

Impact Assessment

The CVSS 3.1 base score is 5.5 (Medium), with the vector CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N. Subscores:

• Confidentiality (C:H): High impact — restricted files may be read, potentially exposing sensitive user or system data.
• Integrity (I:N): No impact — the vulnerability does not allow modification of data.
• Availability (A:N): No impact — no denial of service.
• Attack Vector (AV:L): Local — the attacker must have a presence on the target machine.
• Attack Complexity (AC:L): Low — no special conditions beyond crafting a malicious path.
• Privileges Required (PR:N): None — the attacker does not need elevated privileges to attempt exploitation.
• User Interaction (UI:R): Required — the user must perform some action (e.g., open a file) for the attack to succeed.
• Scope (S:U): Unchanged — the vulnerable component and the impacted component are the same.

Business Impact: For enterprises, the primary risk is data leakage from managed macOS endpoints. A malicious application could bypass TCC controls to read files that macOS normally protects—such as Mail data, Messages history, Safari browsing data, or files in other users' home directories if permissions are misconfigured. While the CVSS score is medium, the high confidentiality impact and the local, low-complexity nature make it a viable component in multi-stage attacks where an attacker already has a foothold via phishing or supply-chain compromise.

Blast Radius: All Macs running affected macOS versions that have not applied the patch are vulnerable. The EPSS score is 0.00175 (7.3rd percentile), indicating a low probability of exploitation in the wild in the next 30 days. CISA KEV does not list this CVE, and no public exploit code or PoC exists, reducing immediate risk. However, the flaw is a classic sandbox/TCC bypass, which is a high-value target for advanced persistent threats and malware (e.g., infostealers) that seek to exfiltrate user data.

Detection Guidance

Sigma Rule

title: Potential macOS Path Traversal File Access Attempt
id: 8f4a1c2e-9b3d-4e5f-a6c7-8d9e0f1a2b3c
status: experimental
description: Detects file access attempts containing directory traversal sequences targeting restricted macOS paths, indicative of CVE-2026-86910 exploitation.
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-86910
author: Valters IT Threat Intelligence
date: 2026-05-12
tags:
  - attack.t1068
  - attack.discovery
logsource:
  product: macos
  category: file_event
  service: endpointsecurity
detection:
  selection_traversal:
    TargetFilename|contains:
      - '../'
      - '..%2f'
      - '..%5c'
      - '/private/etc/'
      - '/Library/Application Support/com.apple.TCC/'
  selection_restricted:
    TargetFilename|endswith:
      - 'TCC.db'
      - 'keychain-2.db'
      - '.ssh/id_rsa'
      - 'Cookies.binarycookies'
  condition: selection_traversal or selection_restricted
falsepositives:
  - Legitimate administrative scripts using relative paths
  - Software installers that access system directories
level: medium

YARA Rule

rule CVE_2026_86910_macOS_PathTraversal
{
    meta:
        description = "Detects strings indicative of path traversal attempts targeting macOS restricted files (CVE-2026-86910)"
        author = "Valters IT Threat Intelligence"
        date = "2026-05-12"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-86910"
        severity = "medium"
    strings:
        $traversal1 = "../" ascii wide
        $traversal2 = "..%2f" ascii wide nocase
        $traversal3 = "..%5c" ascii wide nocase
        $target1 = "/private/etc/" ascii wide
        $target2 = "TCC.db" ascii wide
        $target3 = "keychain-2.db" ascii wide
        $target4 = "Cookies.binarycookies" ascii wide
    condition:
        uint32(0) == 0xFEEDFACF and  // Mach-O 64-bit binary
        (any of ($traversal*)) and
        (any of ($target*))
}

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2026-86910 macOS Path Traversal Attempt"; flow:to_server,established; content:"../"; http_uri; content:"TCC.db"; http_uri; nocase; distance:0; sid:202686910; rev:1; metadata:affected_product macOS, cve CVE-2026-86910, created_at 2026_05_12; classtype:attempted-recon; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-86910;)

Note: This rule is speculative because the vulnerability is local, not network-based. It is included for completeness should an application transmit exploitation artifacts over HTTP. Network detection is inherently limited for local path traversal flaws.

Elastic Detection

process where event.type == "start" and process.name : ("open", "execve", "posix_spawn") and process.args : ("*../*", "*..%2f*", "*/private/etc/*", "*TCC.db*")

This EQL rule triggers when a process launches with arguments containing directory traversal sequences or restricted macOS file paths, suggesting an attempt to access files outside permitted boundaries.

Splunk SPL Query

index=macos sourcetype=osquery:results OR sourcetype=endpoint:file_event
| search (file_path="*../*" OR file_path="*..%2f*" OR file_path="*TCC.db*" OR file_path="*/private/etc/*")
| stats count by host, user, process_name, file_path
| where count > 0
| sort - count

This query surfaces anomalous file access events across managed Macs, enabling analysts to correlate with known vulnerable applications or user-initiated actions.

Wazuh OSSEC Rule

<group name="macos,cve-2026-86910,">
  <rule id="100869" level="10">
    <decoded_as>json</decoded_as>
    <field name="file_path">\.\./|\.\.%2f|/private/etc/|TCC\.db</field>
    <description>CVE-2026-86910: Possible path traversal attempt to access restricted macOS files</description>
    <mitre>
      <id>T1068</id>
    </mitre>
    <group>macos_privilege_escalation,</group>
  </rule>
</group>

This Wazuh rule monitors file event logs for traversal patterns or restricted file targets, generating a high-severity alert for SOC investigation.

Mitigation & Patch Guidance

Patch Confidence: 2/4 (CLAIMED — single source claims patch, not independently confirmed). The NVD description states the issue is fixed in macOS Golden Gate 27, macOS Sequoia 15.8, and macOS Tahoe 26.7. No vendor advisory or independent confirmation is available from the provided data.

1. Immediate Mitigations:

   • Apply the latest macOS security updates as soon as possible: upgrade to Golden Gate 27, Sequoia 15.8, or Tahoe 26.7.
   • Enforce application allowlisting (e.g., via MDM) to prevent untrusted applications from running on managed Macs.
   • Restrict user ability to install unauthorised software and educate users about opening untrusted files.
   • Monitor for anomalous file access attempts using the detection rules above, even if patches are applied, to catch attempted exploitation.

2. Patch/Upgrade Steps:

   • Navigate to System Settings > General > Software Update and install the latest macOS updates.
   • For enterprise fleets, use MDM solutions (Jamf, Kandji, Intune) to push the updates and verify compliance.
   • Confirm the macOS build number matches the patched versions: 27, 15.8, or 26.7.

3. Long-Term Hardening:

   • Implement least-privilege principles: run applications with minimal necessary permissions and avoid granting Full Disk Access unless absolutely required.
   • Regularly audit TCC permissions and file system ACLs on macOS endpoints.
   • Deploy EDR solutions with behavioural detection for path traversal and sandbox escapes.
   • Participate in Apple's security update program and subscribe to vendor advisories for timely patching.

References

1. NVD — CVE-2026-86910: https://nvd.nist.gov/vuln/detail/CVE-2026-86910
2. Apple Security Updates (general): https://support.apple.com/en-us/HT201222
3. CWE-22: Improper Limitation of a Pathname to a Restricted Directory: https://cwe.mitre.org/data/definitions/22.html
4. MITRE ATT&CK T1068 — Exploitation for Privilege Escalation: https://attack.mitre.org/techniques/T1068/
5. CISA Known Exploited Vulnerabilities Catalog (CVE-2026-86910 not listed as of report date): https://www.cisa.gov/known-exploited-vulnerabilities-catalog

Threat Actor Campaigns: No public evidence of exploit-in-the-wild or threat actor campaigns targeting CVE-2026-86910 is available at this time. EPSS score (0.00175) and absence from CISA KEV indicate low exploitation likelihood.

Report generated by Valters IT Threat Intelligence. Technical details are derived strictly from NVD data; no independent verification of vendor patch or exploit availability was performed.