CVE-2026-28933

Executive Summary

CVE-2026-28933 is a use-after-free (UAF) memory-corruption vulnerability in Apple macOS, addressed through improved memory management. It is fixed in macOS Sequoia 15.7.8, macOS Sonoma 14.8.8, and macOS Tahoe 26.6. An attacker able to run a local application can trigger the flaw to cause unexpected system termination, resulting in a denial-of-service condition against the affected host.

Technical Analysis

CVE-2026-28933 is classified under CWE-416 (Use After Free). The NVD description states that "a use-after-free issue was addressed with improved memory management" and that "an app may be able to cause unexpected system termination." The CNA (Apple) did not publish a detailed technical title or a component-specific breakdown in the supplied data.

A use-after-free condition occurs when a program continues to reference a memory region after it has been freed. In the macOS context described here, the flaw is reachable by a locally executing application — the exploit primitive is a local application capable of triggering the vulnerable code path. Successful triggering leads to memory corruption that terminates the system (kernel-level or system-wide crash), i.e., a denial-of-service outcome. The CVSS vector (AV:L, PR:L) confirms that the attacker requires local access and some level of privileges equivalent to running an application in the user's context; no network vector and no user interaction are required.

Because Apple ships macOS components across multiple concurrent release trains, the fix is mirrored in three maintenance branches (Sequoia 15.7.8, Sonoma 14.8.8, Tahoe 26.6). No specific affected subsystem, library, framework, driver, function name, or file path is disclosed in the provided description. Analysts should not assume a particular component; the vulnerability class (memory management defect reachable from a local app) is the reliable basis for detection and mitigation.

No public proof-of-concept, exploit code, or Nuclei template is known. EPSS is very low (0.00148, ~4.4th percentile), indicating minimal predicted exploitation activity in the near term. The CVE is not listed in CISA KEV.

Exploitation Scenarios

No public PoC is available; the attack chain below is inferred strictly at the vulnerability-class level (use-after-free reachable by a local application) from the NVD description and CVSS vector.

1. Reconnaissance / target identification: The attacker identifies a macOS host running a vulnerable version — macOS Sequoia prior to 15.7.8, macOS Sonoma prior to 14.8.8, or macOS Tahoe prior to 26.6. This can be accomplished through local enumeration of OS build/version, or by an insider or already-present threat (e.g., a malicious app distributed to the user) that will execute in the user context.

2. Triggering the flaw class: The attacker causes the vulnerable application (or a local app interacting with the affected macOS component) to execute code paths that allocate, free, and then improperly reference a memory object — the classic use-after-free pattern. Because the issue is a UAF handled by "improved memory management," the flaw is triggered through normal application operations that exercise the affected memory lifecycle; the specific API or component is not disclosed.

3. Payload/execution method (vulnerability-class level): The local application is the delivery vehicle. No network payload, malicious document parameter, or URL endpoint is identified in the source data. The attack does not require user interaction per the CVSS vector (UI:N), though a local actor or a running app is required (AV:L, PR:L).

4. Post-exploitation impact: Per the description, the observable outcome is unexpected system termination — a denial-of-service to the local host. The CVSS vector shows Confidentiality:N and Integrity:N with Availability:H, meaning no data disclosure or modification impact is claimed; impact is limited to availability (crash/reboot). The supplied data does not support claims of code execution, privilege escalation, or persistence.

Impact Assessment

Business impact is availability-focused. A successful trigger causes unexpected system termination, potentially disrupting user productivity and any local workloads on the affected Mac. The CVSS base score is 5.5 (Medium): AV:L (local attack vector), AC:L (low complexity), PR:L (low privileges), UI:N (no user interaction), S:U (unchanged scope), C:N / I:N / A:H (high availability impact only). Blast radius is limited to individual hosts where a local application can run and where the vulnerable macOS version is present. There is no evidence of remote network exploitation, wormable propagation, data theft, or integrity tampering in the provided data. Because no PoC and no in-the-wild exploitation are reported and EPSS is very low, the immediate operational risk is modest, but unpatched fleets remain exposed to local DoS from malicious or defective apps.

Detection Guidance

Sigma Rule

title: Potential macOS Use-After-Free Exploitation Attempt (CVE-2026-28933)
id: 8f2a1c94-3b6e-4d21-9c77-2f0e6a4d9c01
status: experimental
description: Detects repeated unexpected process terminations / kernel panic patterns on macOS consistent with local use-after-free trigger attempts.
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-28933
author: valtersit.com
date: 2026/01/01
tags:
  - attack.t1203
logsource:
  product: macos
  category: process_creation
detection:
  selection_crash:
    Image|endswith:
      - '/ReportCrash'
      - '/panic_dump'
  selection_agent:
    CommandLine|contains:
      - 'ReportCrash'
  condition: selection_crash or selection_agent
falsepositives:
  - Legitimate application crashes unrelated to exploitation
level: low

YARA Rule

rule CVE_2026_28933_macOS_UseAfterFree_Indicator
{
    meta:
        description = "Heuristic indicator for macOS UAF-related crash artifacts (CVE-2026-28933)"
        author = "valtersit.com"
        date = "2026-01-01"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-28933"
        severity = "medium"

    strings:
        $uaf1 = "use-after-free" ascii nocase
        $uaf2 = "Attempted to dereference an already-freed object" ascii nocase
        $uaf3 = "Freed pointer referenced" ascii nocase
        $macos = "macOS" ascii

    condition:
        $macos and any of ($uaf*)
}

Suricata IDS Rule

alert ip any any -> any any (msg:"CVE-2026-28933 macOS Local Use-After-Free DoS - crash telemetry"; flow:to_client; content:"panic"; nocase; content:"macOS"; nocase; within:200; threshold:type limit, track by_src, count 3, seconds 60; classtype:attempted-dos; sid:202628933; rev:1;)

Elastic Detection

process where host.os.type == "macos" and event.action == "process_started" and
  process.name in ("ReportCrash", "panic_dump") and
  process.args : "*crash*"

Splunk SPL Query

index=endpoint sourcetype=macos:system (process_name=ReportCrash OR process_name=panic_dump)
| stats count by host, process_name, _time
| where count > 1
| table _time, host, process_name, count

Wazuh OSSEC Rule

<group name="macos,cve-2026-28933,">
  <rule id="100933" level="6">
    <decoded_as>json</decoded_as>
    <field name="process.name">ReportCrash|panic_dump</field>
    <description>CVE-2026-28933: Possible macOS use-after-free crash/exploitation attempt detected</description>
    <mitre>
      <id>T1203</id>
    </mitre>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 2/4 (CLAIMED — single source claims patch (not independently confirmed)). The only patch source is NVD.

1. Immediate mitigations:

• Restrict execution of untrusted or unsigned local applications on affected macOS hosts; enforce application allowlisting.
• Maintain endpoint protection and crash telemetry collection to detect repeated unexpected terminations.
• Limit local user privileges where operationally feasible (attack requires PR:L).
• Monitor for abnormal app crash frequency as an early indicator.

2. Patch / upgrade steps:

• Upgrade macOS Sequoia to 15.7.8 or later.
• Upgrade macOS Sonoma to 14.8.8 or later.
• Upgrade macOS Tahoe to 26.6 or later.
• Validate the fix via Apple's release notes for the corresponding update before considering the host remediated, since patch provenance here is single-source (NVD) and not independently confirmed.

3. Long-term hardening:

• Adopt a cadence for applying Apple security updates across all supported macOS release trains.
• Track Apple Security Releases pages for correlating CVE identifiers with OS builds.
• Harden against local DoS by minimizing the attack surface available to local apps and using least-privilege user accounts.

References

• NVD — https://nvd.nist.gov/vuln/detail/CVE-2026-28933
• Apple Security Releases — https://support.apple.com/en-us/HT201222
• CWE-416 Use After Free — https://cwe.mitre.org/data/definitions/416.html
• MITRE ATT&CK T1203 — Exploitation for Client Execution — https://attack.mitre.org/techniques/T1203/
• CISA KEV Catalog — https://www.cisa.gov/known-exploited-vulnerabilities-catalog (CVE-2026-28933 is NOT listed as of this report)

No threat actor campaign or exploit-in-the-wild evidence is associated with CVE-2026-28933 in the provided data; EPSS is 0.00148 and no public PoC, Nuclei template, or exploit code exists.