CVE-2026-28827 Overview
CVE-2026-28827 is a path validation vulnerability in Apple macOS that allows a sandboxed application to escape its sandbox. The flaw stems from a parsing issue in the handling of directory paths, classified as [CWE-22] Path Traversal. Apple addressed the issue with improved path validation in macOS Sequoia 15.7.5, macOS Sonoma 14.8.5, and macOS Tahoe 26.4.
Successful exploitation lets a malicious or compromised app break out of the macOS sandbox boundary. This results in elevated access to resources outside the app's confinement, with high impact to confidentiality, integrity, and availability.
Critical Impact
A local app can escape the macOS sandbox via crafted directory paths, gaining access to resources outside its intended security boundary.
Affected Products
- Apple macOS Sequoia prior to 15.7.5
- Apple macOS Sonoma prior to 14.8.5
- Apple macOS Tahoe prior to 26.4
Discovery Timeline
- 2026-03-25 - CVE-2026-28827 published to NVD
- 2026-03-26 - Last updated in NVD database
Technical Details for CVE-2026-28827
Vulnerability Analysis
The vulnerability resides in macOS components responsible for parsing and validating directory paths. When the affected code processes specially crafted path inputs, it fails to correctly normalize or canonicalize the path before enforcing sandbox boundaries. An app running under macOS App Sandbox restrictions can supply paths that resolve outside its allowed container.
The issue is local in nature and does not require user interaction or prior privileges within the sandboxed context. Because the scope changes when the sandbox boundary is crossed, the impact extends beyond the originally confined component. An attacker who controls a sandboxed process can read, modify, or destroy data the process should not reach.
Apple's advisories indicate the fix introduces improved path validation logic to reject malformed or traversal-style inputs before they reach security-sensitive APIs. See the Apple Support Advisory 126794 for component details.
Root Cause
The root cause is improper limitation of a pathname to a restricted directory, consistent with [CWE-22]. The path parser does not consistently resolve segments such as .., symbolic indirections, or unusual separators before enforcing sandbox policy. This mismatch between policy evaluation and final path resolution enables a traversal primitive.
Attack Vector
The attack requires local access, typically delivered by convincing a user to run a malicious app, or by leveraging an already-compromised sandboxed application such as a browser renderer or document viewer. The malicious code constructs directory paths that bypass the sandbox path checks. After the bypass, the process operates with access to files and IPC endpoints outside its container.
No verified public exploit code is available. The vulnerability is described in prose only based on Apple's advisories; see Apple Support Advisory 126795 and Apple Support Advisory 126796 for affected component context.
Detection Methods for CVE-2026-28827
Indicators of Compromise
- Sandboxed processes accessing file paths outside their designated container directory under ~/Library/Containers/<bundle-id>/.
- Unexpected file reads or writes to user home directories, /Library, or /private/var originating from apps with active sandbox entitlements.
- Anomalous open, openat, or stat syscalls referencing paths containing repeated .. segments from sandboxed bundles.
Detection Strategies
- Monitor Endpoint Security Framework (ESF) events ES_EVENT_TYPE_NOTIFY_OPEN and ES_EVENT_TYPE_NOTIFY_CREATE for sandboxed apps touching out-of-container paths.
- Correlate process code signing identifiers and sandbox entitlements with the file paths each process accesses at runtime.
- Hunt for installed application versions on macOS hosts that predate Sequoia 15.7.5, Sonoma 14.8.5, or Tahoe 26.4.
Monitoring Recommendations
- Centralize macOS Unified Log and ESF telemetry to retain file-access events from sandboxed applications.
- Alert on first-seen file path patterns from apps that historically accessed only their container directory.
- Track macOS build versions across the fleet to identify hosts that remain on vulnerable releases.
How to Mitigate CVE-2026-28827
Immediate Actions Required
- Install Apple's security updates: upgrade to macOS Sequoia 15.7.5, macOS Sonoma 14.8.5, or macOS Tahoe 26.4.
- Audit installed third-party applications and remove or restrict apps from untrusted sources until patching completes.
- Verify Gatekeeper and System Integrity Protection (SIP) are enabled on all managed Macs.
Patch Information
Apple released fixes that add improved path validation. Refer to Apple Support Advisory 126794, Apple Support Advisory 126795, and Apple Support Advisory 126796 for the specific build numbers and component notes per macOS train.
Workarounds
- No vendor-supplied workaround exists; apply the security updates.
- Restrict installation of untrusted applications through MDM application allowlisting until patches are deployed.
- Educate users to avoid running unsigned or unverified apps that could leverage the sandbox escape.
# Verify macOS build version against patched releases
sw_vers
# Trigger software update check via MDM or locally
sudo softwareupdate --list
sudo softwareupdate --install --all --restart
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
