CVE-2025-43520: Apple kernel memory write or system crash

Quick Answer

CISA added CVE-2025-43520 to its Known Exploited Vulnerabilities catalog on 2026-03-20, confirming that exploitation has occurred. If you operate Apple Multiple Products, identify the exact version and relevant configuration now, preserve security evidence, and follow the live vendor remediation. A KEV match does not prove your system was compromised, and installing an update does not rule out earlier exploitation.

Last verified: 2026-09-17 UTC. CISA KEV snapshot version 2026.09.16. Recheck the live advisory before changing production.

Context

Status At A Glance

Product scope	Apple — Multiple Products
CVE	CVE-2025-43520
TechGeeks response tier	P0 — confirm an exact match and act now
CISA KEV added	2026-03-20
Vendor severity	Not assigned or published by the vendor in the cited advisory.
CVSS	Not assigned or published by the vendor in the cited advisory.
Ransomware field	Unknown — this is not the same as No; CISA has not marked the field Known.
Forensic-triage field	No in the current CISA field; organizations should still investigate when exposure or evidence warrants it.
CWE	CWE-120
Federal remediation date	2026-04-03 — applies to covered federal agencies; other organizations should set a risk-based deadline.

What Happened

Apple Multiple Products Classic Buffer Overflow Vulnerability. Apple watchOS, iOS, iPadOS, macOS, visionOS, and tvOS contain a classic buffer overflow vulnerability which could allow a malicious application to cause unexpected system termination or write kernel memory. CISA's KEV listing confirms exploitation evidence, but it does not state how widespread the activity is or prove that any particular installation was compromised.

Affected Scope

Kernel code across the cited iOS, iPadOS, macOS, tvOS, visionOS, and watchOS releases. Apple says a malicious application may terminate the system or write kernel memory.

Match the exact edition, hardware or virtual platform, release, patch level, enabled feature, and management exposure. A product-family name alone is not enough to establish applicability.

Steps

What To Do Now

1. Confirm. Inventory every Multiple Products asset and record its exact version, patch level, role, relevant configuration, and exposure.
2. Preserve. Save UTC timestamps, off-device authentication, firewall, proxy, DNS, endpoint, application, and SIEM evidence before logs rotate or a disruptive change removes context.
3. Contain. Restrict unnecessary internet and management-plane access using supported controls. Follow the live advisory: Open the live Apple advisory.
4. Remediate. Install the newest supported Apple operating-system release. Do not remain below the applicable minimum fixed release listed here.
5. Validate. Verify the resulting version or patch level, service health, logging, expected access, an expected denial, and representative dependent workflows.
6. Escalate. If exposure overlapped the vulnerable period or evidence is suspicious, treat the system as a potential incident and follow vendor and incident-response recovery guidance.

Fixed Releases And Mitigation

Investigation And Recovery

CISA added this CVE to KEV in 2026. Apple's cited advisories do not provide indicators of compromise or state that this CVE was exploited; preserve those two facts separately.

When an attacker may have gained administrative, root, SYSTEM, identity, management-plane, or code-execution access, patching alone is not an eradication claim. Preserve evidence, scope affected accounts and downstream systems, rotate exposed credentials or certificates when justified, and rebuild from a trusted source when vendor or incident-response guidance requires it.

Notes

Exploitation Evidence

Vendor statement: A separate vendor exploitation statement was not captured at this check. CISA KEV status independently confirms exploitation evidence.

CISA statement: CVE-2025-43520 was added to KEV on 2026-03-20. The ransomware field is Unknown, and the forensic-triage field is No. These are separate signals.

Validation And Boundaries

This notice does not prove that every product carrying the family name is affected, that exploitation is widespread, that a clean indicator search rules out compromise, or that a successful update restored trust. TechGeeks has not reproduced the exploit and does not replace the vendor advisory, asset inventory, vulnerability scanner, or incident-response process.

Related TechGeeks Resources

• TechGeeks Security Notice Center
• All Security Notices
• What to Do When a Device Hits CISA KEV
• Router CVE Exposure, Version, and Mitigation Checklist
• IoT Firmware Update and End-of-Support Checklist
• Live Protect and Runtime Vulnerability Shielding

References

• Apple security advisory
• Apple security advisory
• Apple security advisory
• Apple security advisory
• Apple security advisory
• Apple security advisory
• Apple security advisory
• Apple security advisory
• NVD CVE record
• CISA source

Wrap-Up

Record whether CVE-2025-43520 applies to your environment. If it does, assign an owner, preserve the change and investigation evidence, complete the vendor action, and document the validated result.

Correction policy: If a primary source changes affected versions, remediation, exploitation status, or recovery guidance, TechGeeks will update this page and its verification date.