High

Out-of-bounds Read in Linux Kernel ipheth NCM NDP16 Parsing

IdentifiersCVE-2025-21742CWE-125· Out-of-bounds Read

CVE-2025-21742 is an out-of-bounds read in the Linux kernel USB iPhone Ethernet (ipheth) driver's handling of NCM-formatted USB receive buffers. The driver accepted an NDP16 offset supplied through the NTH16 header and validated only that the NDP16 start position was within the received URB. Consequently, the fixed-length NDP16 structure could extend beyond the end of the URB. The intended correction uses the format expected from iOS devices, where NDP16 immediately follows NTH16, and validates that the fixed NDP16 portion and a bounded number of datagram-pointer entries fit in the URB. The supplied information notes that enforcing a limit on datagram-pointer entries is separately necessary to fully eliminate the out-of-bounds-read condition.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

A malicious or malformed USB network-device response can cause the kernel to read beyond the received URB boundary while processing iPhone Ethernet NCM data. This may cause a kernel crash and denial of service and could potentially disclose adjacent kernel memory, subject to exploitability constraints not specified here.

Mitigation

If you can’t patch tonight, do this now.

Until a complete kernel fix is deployed, avoid connecting untrusted or potentially malicious USB devices that can present an iPhone Ethernet/NCM interface. Where operationally acceptable, disable or prevent loading of the ipheth driver and restrict physical USB access.

Remediation

Patch, then assume compromise.

Install a Linux kernel update that includes the ipheth NDP16-location validation change and the accompanying enforcement of bounds on NDP16 datagram-pointer entries. Reboot after updating so the patched kernel is running.

PUBLIC EXPLOITS

Exploits

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VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

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VendorProductType

LinuxLinux Kerneloperating_system

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

1 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

1 SOURCESView more in app

redhat accessNews

Jan 1, 2026

RHSA-2025:20095 - Security Advisory - Red Hat Customer Portal

Linux kernel ipheth USB networking driver memory-location flaw.

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Exposure mapping

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Threat actor evidence

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Associated malware

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Detection signatures

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Vendor-by-vendor mapping

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Social activity