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VulnerabilityPublished Updated

CVE-2026-84520: Apple macOS · Buffer Overflow

Affects Apple macOSSource CVE Database V5

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Not known to be exploited · CVSS 9.8 Critical : upgrade to 27 as a priority.

Data as of 30 Oct 2026, 12:04 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CISA-ADPCVSS 3.19.8
EPSS
0.4% chance of exploitation in 30 days – higher than 38% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 27
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 14 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: evidence found.

    Public exploit code: GitHub proofs of concept

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), GitHub proofs of concept, the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade Apple macOS to 27.

Affected software

ProductAffectedFixed in
ApplemacOSAffected
  • <27
Fixed in
  • 27

AI-suggested

Apply the official fix by upgrading to macOS Golden Gate version 27 or later. This update includes improved size validation that resolves the buffer overflow vulnerability.

Description

CVE-2026-84520 is a critical buffer overflow vulnerability in Apple macOS that could allow a local attacker to cause unexpected system termination or corrupt kernel memory. The flaw was addressed by improved size validation and is fixed in macOS Golden Gate version 27.

References

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