CVE-2025-43300: Apple iOS, iPadOS, and macOS Out-of-Bounds Write Vulnerability

CVE-2025-43300 is an out-of-bounds write vulnerability in the Image I/O framework on Apple iOS, iPadOS, and macOS. An attacker who can supply a crafted image may be able to write data outside the intended memory bounds of a process that uses the framework, which can lead to crashes or further compromise depending on the context. Organizations that manage fleets of Apple devices should treat this as a high-priority patching item because Image I/O is used by many applications that handle pictures, documents, and media.

Public detail is limited to the CISA summary and the CWE classification; exact attack vectors, version ranges, and severity metrics must be confirmed against the vendor advisory before making risk decisions.

How it works

The weakness is classified as CWE-787 (Out-of-bounds Write). In an out-of-bounds write, a program writes data past the end (or before the beginning) of an allocated buffer. In this case the vulnerable code resides in Apple’s Image I/O framework, which is responsible for reading and writing a wide range of image formats. When a malformed image is processed, the framework may calculate an incorrect buffer size or offset and then perform a write that overruns that buffer.

An attacker typically abuses this class of flaw by delivering a specially crafted image file—via email attachment, web page, messaging app, or any other channel that causes the Image I/O framework to parse the file. Successful exploitation can corrupt memory, crash the process, or, under the right conditions, allow arbitrary code execution with the privileges of the affected process. No public exploit details or proof-of-concept code are supplied in the available facts; defenders should assume that weaponization is possible once an advisory is published and should verify any claims of in-the-wild use against official sources.

Am I affected? How to find it in your systems

The vulnerability affects Apple iOS, iPadOS, and macOS devices that include the Image I/O framework. Virtually every modern Apple device ships with this framework because it is used by the Photos app, Safari, Mail, Messages, Preview, and many third-party applications that handle images.

• Inventory all managed iOS, iPadOS, and macOS endpoints via your MDM or asset-management platform. Record the exact OS build number for each device.
• Compare those build numbers against the fixed versions listed in Apple’s security advisory for CVE-2025-43300. Do not rely on major version numbers alone; confirm the precise build.
• Identify applications or workflows that process untrusted images (email gateways, content-management systems, user-uploaded media, etc.) and note which of them invoke Image I/O on the affected platforms.
• Review crash logs and diagnostic reports for Image I/O-related faults or unexpected process terminations that coincide with image-handling activity; such telemetry can indicate attempted exploitation even if no successful compromise is confirmed.

If your inventory tools cannot report OS build numbers accurately, treat every unmanaged or outdated device as potentially vulnerable until proven otherwise.

How to remediate

The primary remediation is to apply the vendor-supplied update that addresses CVE-2025-43300. Follow Apple’s published instructions for iOS, iPadOS, and macOS; install the security update through the normal software-update mechanism or via your MDM as soon as it is available and tested in your environment.

• Prioritize devices that process untrusted images or that are exposed to the internet or guest networks.
• After patching, verify the installed build number matches the fixed version listed in the advisory.
• For cloud-hosted Apple services or managed device fleets, also follow any applicable BOD 22-01 guidance as noted by CISA.
• If mitigations are unavailable for a particular product or configuration, CISA advises discontinuing use of that product until a fix can be applied.

Once the patch is deployed, re-baseline configuration and vulnerability-scan results so that future drift can be detected quickly.

If you can't patch immediately

When immediate patching is not feasible, apply compensating controls that reduce the likelihood or impact of successful exploitation.

• Segment devices that handle untrusted images onto restricted network zones with limited outbound connectivity.
• Use mobile-device or endpoint-management policies to block installation of unapproved apps that process images, and disable automatic image loading in Mail, Messages, and Safari where business needs allow.
• Deploy virtual-patching rules on web application firewalls or secure email gateways that inspect image attachments for known malformed structures associated with Image I/O issues (confirm signatures against current threat intelligence).
• Increase monitoring of process crashes, memory-corruption events, and anomalous Image I/O activity; forward relevant logs to a SIEM for correlation.
• Enforce least-privilege execution so that any process that does parse images runs with minimal rights, limiting the blast radius of a successful write.

These measures do not eliminate the vulnerability; they only buy time until the official update can be installed.

If your data may have been exposed

Actively exploited vulnerabilities of this class can lead to device compromise and subsequent data exposure. If you have reason to believe an unpatched device processed a malicious image, treat the incident as a potential breach: isolate the device, collect forensic artifacts, and begin standard incident-response procedures. Known ransomware use of this specific CVE is not documented in the available facts. As a quick check for prior credential or personal-data exposure, you can run a free exposure scan of your email address against known breach data sets.