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CVE Record

CVE-2025-38557: HID: apple: validate feature-report field count to prevent NULL pointer dereference

In the Linux kernel, the following vulnerability has been resolved: HID: apple: validate feature-report field count to prevent NULL pointer dereference A malicious HID device with quirk APPLE_MAGIC_BACKLIGHT can trigger a NULL pointer dereference whilst the power feature-report is toggled and sent to the device in apple_magic_backlight_report_set(). The power feature-report is expected to have two data fields, but if the descriptor declares one field then accessing field[1] and dereferencing it in apple_magic_backlight_report_set() becomes invalid since field[1] will be NULL. An example of a minimal descriptor which can cause the crash is something like the following where the report with ID 3 (power report) only references a single 1-byte field. When hid core parses the descriptor it will encounter the final feature tag, allocate a hid_report (all members of field[] will be zeroed out), create field structure and populate it, increasing the maxfield to 1. The subsequent field[1] access and dereference causes the crash. Usage Page (Vendor Defined 0xFF00) Usage (0x0F) Collection (Application) Report ID (1) Usage (0x01) Logical Minimum (0) Logical Maximum (255) Report Size (8) Report Count (1) Feature (Data,Var,Abs) Usage (0x02) Logical Maximum (32767) Report Size (16) Report Count (1) Feature (Data,Var,Abs) Report ID (3) Usage (0x03) Logical Minimum (0) Logical Maximum (1) Report Size (8) Report Count (1) Feature (Data,Var,Abs) End Collection Here we see the KASAN splat when the kernel dereferences the NULL pointer and crashes: [ 15.164723] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000006: 0000 [#1] SMP KASAN NOPTI [ 15.165691] KASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037] [ 15.165691] CPU: 0 UID: 0 PID: 10 Comm: kworker/0:1 Not tainted 6.15.0 #31 PREEMPT(voluntary) [ 15.165691] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 [ 15.165691] RIP: 0010:apple_magic_backlight_report_set+0xbf/0x210 [ 15.165691] Call Trace: [ 15.165691] <TASK> [ 15.165691] apple_probe+0x571/0xa20 [ 15.165691] hid_device_probe+0x2e2/0x6f0 [ 15.165691] really_probe+0x1ca/0x5c0 [ 15.165691] __driver_probe_device+0x24f/0x310 [ 15.165691] driver_probe_device+0x4a/0xd0 [ 15.165691] __device_attach_driver+0x169/0x220 [ 15.165691] bus_for_each_drv+0x118/0x1b0 [ 15.165691] __device_attach+0x1d5/0x380 [ 15.165691] device_initial_probe+0x12/0x20 [ 15.165691] bus_probe_device+0x13d/0x180 [ 15.165691] device_add+0xd87/0x1510 [...] To fix this issue we should validate the number of fields that the backlight and power reports have and if they do not have the required number of fields then bail.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This is a Linux kernel crash bug in the Apple HID driver. A malicious HID device can present an unexpected report layout and cause a NULL pointer dereference, crashing the kernel. The public sources support denial-of-service impact, not data theft or remote compromise.

Executive priority

Treat this as a focused availability risk, not a broad internet-facing emergency. Patch through normal kernel maintenance, faster where untrusted peripherals are realistic.

Technical view

The apple HID driver expects specific backlight and power feature reports. If an APPLE_MAGIC_BACKLIGHT device descriptor declares too few fields, apple_magic_backlight_report_set() can dereference field[1] when it is NULL. The kernel fix validates report field counts and exits when reports are malformed.

Likely exposure

Exposure is most relevant for Linux systems running affected kernel versions that may connect to untrusted or malicious HID devices matching this driver path. Distro kernel backports may differ, so version-only checks are insufficient.

Exploitation context

The CVE record says KEV is false and the supplied sources do not cite active exploitation. Exploitation requires a malicious HID device descriptor reaching the affected Apple HID backlight logic. The demonstrated outcome is a kernel crash.

Researcher notes

Evidence is limited to the CVE description and kernel stable references. No CVSS, CWE, exploit-in-the-wild claim, or product scope beyond Linux kernel Apple HID behavior is provided.

Mitigation direction

  • Apply a vendor kernel update containing the referenced stable fixes.
  • Confirm distro advisories because fixes may be backported without changing major kernel versions.
  • Restrict connection of untrusted HID devices until affected systems are patched.
  • Prioritize shared workstations, kiosks, labs, and systems exposed to removable peripherals.

Validation and detection

  • Inventory Linux kernel versions and distro package build numbers on exposed systems.
  • Check whether the vendor kernel includes the referenced apple HID field-count validation fix.
  • Review asset classes where users or attackers can attach HID devices.
  • After updating, verify normal Apple HID backlight functionality still works.
Prepared
Confidence
high
Sources
6

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

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.

0CVSS vectors
3Timeline events
0ADP providers
5Source links

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

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Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux394ba612f9419ec5bfebbffb72212fd3b2094986, 394ba612f9419ec5bfebbffb72212fd3b2094986, 394ba612f9419ec5bfebbffb72212fd3b2094986, 394ba612f9419ec5bfebbffb72212fd3b2094986unaffected
LinuxLinux6.11, 0, 6.12.42, 6.15.10, 6.16.1, 6.17affected
Weakness

CWE details

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