Security readout for executives and security teams
Plain-English summary
A network attacker may bypass valid credentials and access Screen Sharing on vulnerable Macs. Successful compromise could expose sensitive information, allow unauthorized changes, and disrupt systems. Apple fixed the issue in current updates for Tahoe, Sequoia, and Sonoma.
Executive priority
Treat this as an emergency patching issue. Prioritize network-reachable Macs and systems handling privileged or sensitive work. Because CISA lists the vulnerability as exploited, deferment increases exposure even though public details about observed attacks remain limited.
Technical view
CVE-2026-65400 is a CWE-287 authentication flaw caused by inadequate state management in macOS Screen Sharing. It is remotely reachable, requires no privileges or user interaction, and has a CVSS 3.1 score of 9.8. Precise vulnerable version ranges are not supplied, but Apple identifies fixed releases.
Likely exposure
Exposure is most likely on Macs running releases earlier than macOS Tahoe 26.6.1, Sequoia 15.7.9, or Sonoma 14.8.9 where Screen Sharing is network-reachable. The supplied sources do not enumerate every vulnerable build or clarify whether default configurations are affected.
Exploitation context
CISA's Known Exploited Vulnerabilities listing supports active exploitation. The supplied evidence does not describe campaign scale, targeted organizations, attacker behavior, indicators of compromise, or prerequisites beyond network access to Screen Sharing.
Researcher notes
The evidence attributes the flaw to authentication state management but provides no protocol-level root cause, affected component version matrix, exploit conditions beyond network access, or detection artifacts. Avoid assuming all earlier macOS releases are affected; validate applicability through Apple's advisories and asset-specific version data.
Mitigation direction
- Update Tahoe systems to macOS 26.6.1 or later.
- Update Sequoia systems to macOS 15.7.9 or later.
- Update Sonoma systems to macOS 14.8.9 or later.
- Until updated, disable or restrict Screen Sharing where operationally feasible.
- Consult Apple guidance for unsupported macOS versions.
Validation and detection
- Inventory macOS versions across managed and unmanaged Macs.
- Verify installed builds meet the applicable fixed release.
- Identify systems with Screen Sharing enabled and network-reachable.
- Review Screen Sharing records for unexpected sessions; supplied sources provide no specific indicators.
- Confirm compensating network restrictions remain effective until updates complete.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-287: Credential and account abuse lookup
Authentication and credential weaknesses can make valid-account abuse and credential telemetry useful review starting points. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-65400 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.8 (3.1)
- Known Exploited
- Yes
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CISA KEV status
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9CISA-ADPVulnerability scoring details
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- Added to KEVCISA-ADP
CISA Known Exploited Vulnerabilities metadata lists this CVE as known exploited.
- ADP timelineCISA-ADP
CVE-2026-65400 added to CISA KEV
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
- 2026-08-18T00:00:00.000Z: CVE-2026-65400 added to CISA KEV
Source materials
- CVE List V5 sourceCVE List V5
- https://support.apple.com/en-us/148170CVE reference, apple
- https://support.apple.com/en-us/148171CVE reference, apple
- https://support.apple.com/en-us/148172CVE reference, apple
- https://advisories.ncsc.nl/2026/ncsc-2026-0280.htmlCVE reference, CISA-ADP · third-party-advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-65400CVE reference, CISA-ADP · government-resource
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Authentication
Improper Authentication represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.