Apple Patches Meta-Reported Zero-Day Linked to ‘Extremely Sophisticated Attack’

CVE-2025-43300 is an out-of-bounds write (CWE-787) in the Image I/O (ImageIO) framework used by Apple iOS, iPadOS, and macOS. It can be triggered when a device processes a specially crafted image file, corrupting memory in the image-parsing process. Successful exploitation may cause application crashes or allow arbitrary code execution with the privileges of the application handling the image. Because ImageIO is a core system component on essentially every Apple device, virtually all users of iPhones, iPads, and Macs are exposed. The flaw is being exploited in the wild — CISA added it to the KEV catalog on 2025-08-21, mandating patching per BOD 22-01 for federal agencies — and EPSS estimates a 22% probability of exploitation in the next 30 days (98th percentile); no public PoC is known and ransomware use is unconfirmed.

Do: Apply Apple's security updates for iOS, iPadOS, and macOS issued in August 2025 (e.g., iOS 18.6.1 / iPadOS 18.6.1 and macOS Sequoia 15.6.1) on all devices, prioritizing user-facing fleets and agencies bound by BOD 22-01 deadlines. Until devices are patched, exercise caution with images from untrusted sources (email, messaging, web content), since no compensating mitigations are specified. Note that the source data does not enumerate exact affected builds, so verify coverage against Apple's advisory and CISA KEV required actions.

CVE-2025-55177 is an incorrect authorization flaw (CWE-863) in how WhatsApp for iOS, WhatsApp Business for iOS, and WhatsApp for Mac validate linked device synchronization messages, allowing an unrelated user to trigger processing of content from an arbitrary URL on a target's device. An attacker can reach a vulnerable client through the messaging channel without normal authorization checks, causing the app to fetch or process attacker-chosen content. On its own the flaw carries only partial confidentiality and integrity impact (CVSS 5.4), but Meta assesses it was chained with an Apple OS vulnerability (CVE-2025-43300) in a sophisticated attack against specific, targeted users. Users running WhatsApp for iOS before 2.25.21.73, WhatsApp Business for iOS before 2.25.21.78, or WhatsApp for Mac before 2.25.21.78 are affected. The flaw was added to CISA's KEV catalog on 2025-09-02 amid reports of highly targeted zero-day attacks, though no public proof-of-concept is known and use in ransomware campaigns has not been reported.

Do: Update WhatsApp for iOS to v2.25.21.73 or later, WhatsApp Business for iOS to v2.25.21.78 or later, and WhatsApp for Mac to v2.25.21.78 or later. Also apply Apple's backported OS fix for CVE-2025-43300, since the two flaws were combined in the observed attack chain. Review and re-link WhatsApp companion devices if compromise is suspected; federal agencies must follow BOD 22-01 required-action deadlines per the KEV listing.

An out-of-bounds write vulnerability (CWE-787) in Apple's CoreGraphics framework, scored 8.8 (high), allows arbitrary code execution when a device processes a maliciously crafted file, such as a malicious image or document that triggers the vulnerable rendering path. The flaw affects iPhones, iPads, and Macs, and exploitation requires no privileges but does require user interaction — the victim must open or preview the malicious file. Successful exploitation gives the attacker the ability to run code with high impact on confidentiality, integrity, and availability of the affected device. Apple states it is aware of a report that this issue may have been exploited in an extremely sophisticated attack against specific targeted individuals on versions of iOS before iOS 27, indicating likely limited but real in-the-wild use. Fixes were shipped in iOS 26.7.1, iPadOS 26.7.1, macOS Sequoia 15.8.1, and macOS Tahoe 26.7.1.

Do: Patch immediately to iOS 26.7.1 / iPadOS 26.7.1 on mobile and macOS Sequoia 15.8.1 or macOS Tahoe 26.7.1 on Macs; push these updates via MDM and verify fleet-wide compliance. Because the attack requires the victim to process a maliciously crafted file, advise users — especially journalists, activists, executives, and other likely targets of sophisticated attacks — not to open unsolicited attachments or media files from unknown senders. Review device logs and EDR telemetry for anomalous process activity following the opening of unexpected files on unpatched devices.