Vulnerability

CVE-2026-65400

Critical· 9.8KEVCVSS9.8EPSS2%

.rules3/5

Apple macOS Improper Authentication Vulnerability

Apple macOS contains an improper authentication vulnerability that could allow an attacker on the network to authenticate to Screen Sharing without valid credentials.

Threat signal

100/100

Severe

Severity

critical

CVSS

9.8

EPSS

Active

KEV

CISA KEV — actively exploited

61d overdue

AffectedApple — macOS

Added to KEV

2026-08-18

Federal patch due (BOD 22-01)

2026-08-21

Required action (CISA verbatim)

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.

Vendor advisory + references

CISA description: “Apple macOS contains an improper authentication vulnerability that could allow an attacker on the network to authenticate to Screen Sharing without valid credentials.”

CVSS

v3.1via NVDOpen in FIRST calculator →

9.8/ 10CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack VectorNetworkExploitable remotely over the internet — no local access needed.
Attack ComplexityLowNo special conditions — exploit works reliably.
Privileges RequiredNoneUnauthenticated — no credentials needed.
User InteractionNoneFully automated — no victim action needed.
ScopeUnchangedImpact contained to the vulnerable component.
Confidentiality ImpactHighTotal disclosure of sensitive data.
Integrity ImpactHighTotal compromise of integrity — full data modification possible.
Availability ImpactHighTotal loss of availability — full DoS possible.

EPSS

Exploit prediction · 30-day horizonFIRST.org →

1.72%

probability of exploitation in next 30 days

p77

higher than 77% of all CVEs

8-day trend↑ 0pp

Mid-pack — moderate exploitation likelihood.

Vendor VEX

No VEX statements published for CVE-2026-65400. Vendors publish VEX (Vulnerability Exploitability eXchange) to assert per-product whether a CVE is actually exploitable in their distribution.

SSVCAct

Active exploitation with total impact on essential/support systems

exploitation: active
automatable: yes
impact: total
mission: support

Lifecycle

2026-08-18Added to CISA KEVransomware: Unknown
2026-08-18Published
2026-08-18Last modified2 sources
2026-08-21Federal patch due (BOD 22-01)

Mentions in news & research

research:huntressFrom Screen Share to Root Access: Breaking Down CVE-2026-43760 and CVE-2026-65400 on macOS2026-08-07