CVE-2026-84509

Malicious SMB Server Triggers Out‑of‑Bounds Read Leading to System Crash

Published Sep 14, 2026 CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed
Description
An out-of-bounds read was addressed with improved bounds checking. This issue is fixed in macOS Golden Gate 27, macOS Sequoia 15.8, macOS Tahoe 26.7. Connecting to a malicious SMB server may lead to unexpected system termination.

Analysis

AI-generated

Technical impact

An out-of-bounds read occurs when the macOS SMB client processes data received from a malicious SMB server, which can trigger an unexpected system shutdown. The flaw is a memory safety error that enables a remote attacker to read memory beyond the intended bounds, potentially causing a crash and disrupting user operations.

Affected Systems

Apple macOS is affected. The vulnerability is fixed in macOS Golden Gate 27, macOS Sequoia 15.8, and macOS Tahoe 26.7. Vulnerable releases can crash when they connect to a malformed SMB server.

Risk and Exploitability

The flaw is exploitable remotely via a malicious SMB server connection, requiring network access to the target. While the EPSS score is less than 1% and it is not listed in KEV, the nature of the vulnerability suggests that attackers could use it to cause service disruption on any exposed SMB interface. No proof‑of‑concept was reported, but the lack of a prepared mitigation makes the risk significant for environments that maintain SMB access.

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

  • Upgrade macOS to the latest available release (Golden Gate 27, Sequoia 15.8, or Tahoe 26.7) to apply the bounds‑checking fix.
  • Limit SMB client traffic to trusted servers or networks, and disable SMB connections if not required.
  • Apply any available security updates promptly, ensuring that the patch level includes the SMB read‑check improvement.

Generated by OpenCVE AI on September 20, 2026 at 19:16 UTC.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Title Malicious SMB Server Triggers Out‑of‑Bounds Read Leading to System Crash
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
CPEs cpe:2.3:o:apple:macos:*:*:*:*:*:*:*:*
Type Values Removed Values Added
Weaknesses CWE-125
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H'}

Type Values Removed Values Added
Title Out‑of‑Bounds Read in SMB Client Causes Unexpected System Termination
Weaknesses CWE-788
Type Values Removed Values Added
Title Out‑of‑Bounds Read in SMB Client Causes Unexpected System Termination
Weaknesses CWE-788
Type Values Removed Values Added
First Time appeared Apple
Apple macos
Vendors & Products Apple
Apple macos
Type Values Removed Values Added
Description An out-of-bounds read was addressed with improved bounds checking. This issue is fixed in macOS Golden Gate 27, macOS Sequoia 15.8, macOS Tahoe 26.7. Connecting to a malicious SMB server may lead to unexpected system termination.
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
apple
Published
Updated
Oct 26, 2026, 8:39 PM
Reserved
Sep 1, 2026, 9:13 PM
Status
Analyzed
Published
Sep 14, 2026, 9:17 PM
Modified
Sep 17, 2026, 4:56 PM