---
title: "CVE-2026-65400: Apple macOS Improper Authentication Vulnerability"
url: https://erroneo.us/security/cve/CVE-2026-65400/
description: "CVE-2026-65400 (Apple macOS): Exploited in the wild (CISA KEV). An authentication issue was addressed with improved state management. This issue is fixed in…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-08-06
date_modified: 2026-09-14
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-65400"
kev: true
cvss: 9.8
epss: 0.01723
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-65400: Apple macOS Improper Authentication Vulnerability

**Signal:** Exploited: patch now if you run it. CISA has confirmed exploitation in the wild. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Yes, if you run Apple macOS. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2026-08-18, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2026-08-21 ; treat that as the outer limit, not the target.
- EPSS 1.7% , percentile 77: FIRST’s model estimates a 1.7% chance of exploitation activity in the next 30 days, higher than 77% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Editorial verdict: Check exposure. macOS Screen Sharing CVE-2026-65400: Exploited Auth Bypass — Any Mac with Screen Sharing or Remote Management reachable from an untrusted network needs the update today and a compromise check; Macs with the service off should still update, but they were not reachable by this attack.

## What it is

An authentication issue was addressed with improved state management. This issue is fixed in macOS Golden Gate 27, macOS Sequoia 15.7.9, macOS Sonoma 14.8.9, macOS Tahoe 26.6.1, macOS Tahoe 26.7. An attacker on the network may be able to authenticate to Screen Sharing without valid credentials.

## Affected products (CVE record)

- Apple macOS: < 14.8.9, < 15.7.9, < 26.6.1, < 26.7, < 27

## Severity

- CISA-ADP CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`

## Exploitation

- CISA KEV: added 2026-08-18; federal due date 2026-08-21. Known ransomware use: Unknown.
- CISA required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
- CISA SSVC assessment: exploitation active , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 1.72% probability of exploitation activity in the next 30 days; percentile 77.

## Sources

- [Listed in CISA KEV notes (support.apple.com)](https://support.apple.com/en-us/148170)
- [Listed in CISA KEV notes (support.apple.com)](https://support.apple.com/en-us/148171)
- [Listed in CISA KEV notes (support.apple.com)](https://support.apple.com/en-us/148172)
- [CVE.org record CVE-2026-65400](https://www.cve.org/CVERecord?id=CVE-2026-65400)
- [NVD entry CVE-2026-65400](https://nvd.nist.gov/vuln/detail/CVE-2026-65400)
- [CISA Known Exploited Vulnerabilities catalog entry](https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-65400)
- [Listed in CISA KEV notes (cisa.gov)](https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk)
- [Listed in CISA KEV notes (cisa.gov)](https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk)
- [support.apple.com](https://support.apple.com/en-us/149035)
- [support.apple.com](https://support.apple.com/en-us/149042)
- [advisories.ncsc.nl](https://advisories.ncsc.nl/2026/ncsc-2026-0280.html)
- [seclists.org](http://seclists.org/fulldisclosure/2026/Aug/36)
- [seclists.org](http://seclists.org/fulldisclosure/2026/Aug/37)

---
Source page: https://erroneo.us/security/cve/CVE-2026-65400/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt