Summary
In the Linux kernel, the following vulnerability has been resolved: USB: hub: Ignore non...
In the Linux kernel, the following vulnerability has been resolved:
USB: hub: Ignore non-compliant devices with too many configs or interfaces
Robert Morris created a test program which can cause
usb_hub_to_struct_hub() to dereference a NULL or inappropriate
pointer:
Oops: general protection fault, probably for non-canonical address
0xcccccccccccccccc: 0000 [#1] SMP DEBUG_PAGEALLOC PTI
CPU: 7 UID: 0 PID: 117 Comm: kworker/7:1 Not tainted 6.13.0-rc3-00017-gf44d154d6e3d #14
Hardware name: FreeBSD BHYVE/BHYVE, BIOS 14.0 10/17/2021
Workqueue: usb_hub_wq hub_event
RIP: 0010:usb_hub_adjust_deviceremovable+0x78/0x110
...
Call Trace:
? die_addr+0x31/0x80
? exc_general_protection+0x1b4/0x3c0
? asm_exc_general_protection+0x26/0x30
? usb_hub_adjust_deviceremovable+0x78/0x110
hub_probe+0x7c7/0xab0
usb_probe_interface+0x14b/0x350
really_probe+0xd0/0x2d0
? __pfx___device_attach_driver+0x10/0x10
__driver_probe_device+0x6e/0x110
driver_probe_device+0x1a/0x90
__device_attach_driver+0x7e/0xc0
bus_for_each_drv+0x7f/0xd0
__device_attach+0xaa/0x1a0
bus_probe_device+0x8b/0xa0
device_add+0x62e/0x810
usb_set_configuration+0x65d/0x990
usb_generic_driver_probe+0x4b/0x70
usb_probe_device+0x36/0xd0
The cause of this error is that the device has two interfaces, and the
hub driver binds to interface 1 instead of interface 0, which is where
usb_hub_to_struct_hub() looks.
We can prevent the problem from occurring by refusing to accept hub
devices that violate the USB spec by having more than one
configuration or interface.
Impact
The application dereferences a null pointer, causing a crash. Typical impact: denial of service via crash.
CVE-2025-21776 has a CVSS score of 5.5 (Medium). The vector is requires local access, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2025-21776? CVE-2025-21776 is a medium-severity null pointer dereference vulnerability. No fixed version is listed yet. The application dereferences a null pointer, causing a crash.
- How severe is CVE-2025-21776? CVE-2025-21776 has a CVSS score of 5.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Is there a fix for CVE-2025-21776? No fixed version is listed for CVE-2025-21776 yet. Monitor the advisory for updates and apply mitigations in the interim.
- Is CVE-2025-21776 exploitable, and should I be worried? Whether CVE-2025-21776 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2025-21776 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.