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Exploited vulnerability · CISA KEV

Is CVE-2026-65400 exploited? Yes: in CISA KEV since 18 Aug 2026

Gociux · Apple macOS · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2026-65400, Apple macOS Improper Authentication Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 18 Aug 2026, 12 days after it was published. It affects Apple macOS. If you run it, CISA's required action is: 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.

exploitedYesCISA KEV · 18 Aug 2026
ransomwareNot knownno confirmed use
EPSStop 5%very likely to be exploited
severity9.8CVSS 3.1 · critical
US federal due21 Aug 2026BOD 22-01 deadline

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.

VendorApple (96 exploited CVEs in KEV)
ProductmacOS
VulnerabilityApple macOS Improper Authentication Vulnerability
WeaknessCWE-287
Published6 Aug 2026
Added to KEV18 Aug 2026
Reported by (CNA)apple

What to do

  1. Check whether you run it. Look for macOS in your asset inventory, including appliances and cloud images. Stack check lists every exploited Apple CVE at once.
  2. Apply the fix. 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.
  3. If you can't patch today, take the affected service off the internet or restrict who can reach it, and check its logs for signs of compromise since 6 Aug 2026.
  4. Get told next time. Email alerts when CISA adds a CVE for Apple.

Other exploited CVEs in macOS

References

Questions

Is CVE-2026-65400 being exploited?

Yes. CISA added CVE-2026-65400 to the Known Exploited Vulnerabilities catalog on 18 Aug 2026, which means there is reliable evidence of exploitation in the wild.

Is CVE-2026-65400 used in ransomware attacks?

CISA does not list known ransomware use for it. That can change, and exploitation alone is reason to fix it first.

How do I fix CVE-2026-65400?

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. Check Apple's advisory for the fixed versions, and if you can't patch quickly, restrict access to the affected macOS and watch it for signs of compromise.

Sources: CISA KEV (exploitation, ransomware use, required action, due date), the CVE record (publication date, CVSS, CNA), NVD and FIRST EPSS (live score). More: all KEV additions in August 2026 · Apple scorecard · act-now radar.

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