CVE-2026-65400: Apple macOS Improper Authentication Vulnerability
What it is
Apple macOS contains an improper authentication vulnerability that could allow an attacker on the network to authenticate to Screen Sharing without valid credentials.
What to do
Treat this as urgent. Identify every affected system, starting with anything internet-facing, and apply the vendor fix or mitigation within days. If you cannot patch quickly, isolate or disable the affected service and watch for signs of compromise.
- Priority
- Act now: Patch or mitigate internet-facing systems within days.
- Severity (CVSS)
- 9.8 critical
- CISA assessment (SSVC)
- actively exploited; attackers can automate it at scale; total control of the affected system
- Exploit probability (EPSS, 30 days)
- 1.7%, higher than 76% of all CVEs
- Added to CISA KEV
- 18 August 2026
- CISA fix-by date
- 21 August 2026 (US federal agencies; a sensible deadline for everyone)
- Ransomware use
- Not known
- Weakness
- CWE-287
References
- NIST NVD entry
- CISA KEV entry
- support.apple.com/en-us/148170
- support.apple.com/en-us/148171
- support.apple.com/en-us/148172
- support.apple.com/en-us/149035
- support.apple.com/en-us/149042
- seclists.org/fulldisclosure/2026/Aug/36
Sources: CISA Known Exploited Vulnerabilities · FIRST Exploit Prediction Scoring System (EPSS) · NIST National Vulnerability Database · CISA Vulnrichment (SSVC), via the CVE Program. This product uses data from the NVD API but is not endorsed or certified by the NVD. Summaries are machine-written from CISA’s description; treat the vendor’s advisory as the authority for fixes.