CVE-2025-40016
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-10-20

Last updated on: 2026-04-18

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: media: uvcvideo: Mark invalid entities with id UVC_INVALID_ENTITY_ID Per UVC 1.1+ specification 3.7.2, units and terminals must have a non-zero unique ID. ``` Each Unit and Terminal within the video function is assigned a unique identification number, the Unit ID (UID) or Terminal ID (TID), contained in the bUnitID or bTerminalID field of the descriptor. The value 0x00 is reserved for undefined ID, ``` If we add a new entity with id 0 or a duplicated ID, it will be marked as UVC_INVALID_ENTITY_ID. In a previous attempt commit 3dd075fe8ebb ("media: uvcvideo: Require entities to have a non-zero unique ID"), we ignored all the invalid units, this broke a lot of non-compatible cameras. Hopefully we are more lucky this time. This also prevents some syzkaller reproducers from triggering warnings due to a chain of entities referring to themselves. In one particular case, an Output Unit is connected to an Input Unit, both with the same ID of 1. But when looking up for the source ID of the Output Unit, that same entity is found instead of the input entity, which leads to such warnings. In another case, a backward chain was considered finished as the source ID was 0. Later on, that entity was found, but its pads were not valid. Here is a sample stack trace for one of those cases. [ 20.650953] usb 1-1: new high-speed USB device number 2 using dummy_hcd [ 20.830206] usb 1-1: Using ep0 maxpacket: 8 [ 20.833501] usb 1-1: config 0 descriptor?? [ 21.038518] usb 1-1: string descriptor 0 read error: -71 [ 21.038893] usb 1-1: Found UVC 0.00 device <unnamed> (2833:0201) [ 21.039299] uvcvideo 1-1:0.0: Entity type for entity Output 1 was not initialized! [ 21.041583] uvcvideo 1-1:0.0: Entity type for entity Input 1 was not initialized! [ 21.042218] ------------[ cut here ]------------ [ 21.042536] WARNING: CPU: 0 PID: 9 at drivers/media/mc/mc-entity.c:1147 media_create_pad_link+0x2c4/0x2e0 [ 21.043195] Modules linked in: [ 21.043535] CPU: 0 UID: 0 PID: 9 Comm: kworker/0:1 Not tainted 6.11.0-rc7-00030-g3480e43aeccf #444 [ 21.044101] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014 [ 21.044639] Workqueue: usb_hub_wq hub_event [ 21.045100] RIP: 0010:media_create_pad_link+0x2c4/0x2e0 [ 21.045508] Code: fe e8 20 01 00 00 b8 f4 ff ff ff 48 83 c4 30 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc 0f 0b eb e9 0f 0b eb 0a 0f 0b eb 06 <0f> 0b eb 02 0f 0b b8 ea ff ff ff eb d4 66 2e 0f 1f 84 00 00 00 00 [ 21.046801] RSP: 0018:ffffc9000004b318 EFLAGS: 00010246 [ 21.047227] RAX: ffff888004e5d458 RBX: 0000000000000000 RCX: ffffffff818fccf1 [ 21.047719] RDX: 000000000000007b RSI: 0000000000000000 RDI: ffff888004313290 [ 21.048241] RBP: ffff888004313290 R08: 0001ffffffffffff R09: 0000000000000000 [ 21.048701] R10: 0000000000000013 R11: 0001888004313290 R12: 0000000000000003 [ 21.049138] R13: ffff888004313080 R14: ffff888004313080 R15: 0000000000000000 [ 21.049648] FS: 0000000000000000(0000) GS:ffff88803ec00000(0000) knlGS:0000000000000000 [ 21.050271] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 21.050688] CR2: 0000592cc27635b0 CR3: 000000000431c000 CR4: 0000000000750ef0 [ 21.051136] PKRU: 55555554 [ 21.051331] Call Trace: [ 21.051480] <TASK> [ 21.051611] ? __warn+0xc4/0x210 [ 21.051861] ? media_create_pad_link+0x2c4/0x2e0 [ 21.052252] ? report_bug+0x11b/0x1a0 [ 21.052540] ? trace_hardirqs_on+0x31/0x40 [ 21.052901] ? handle_bug+0x3d/0x70 [ 21.053197] ? exc_invalid_op+0x1a/0x50 [ 21.053511] ? asm_exc_invalid_op+0x1a/0x20 [ 21.053924] ? media_create_pad_link+0x91/0x2e0 [ 21.054364] ? media_create_pad_link+0x2c4/0x2e0 [ 21.054834] ? media_create_pad_link+0x91/0x2e0 [ 21.055131] ? _raw_spin_unlock+0x1e/0x40 [ 21.055441] ? __v4l2_device_register_subdev+0x202/0x210 [ 21.055837] uvc_mc_register_entities+0x358/0x400 [ 21.056144] uvc_register_chains+0x1 ---truncated---
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Meta Information
Published
2025-10-20
Last Modified
2026-04-18
Generated
2026-05-07
AI Q&A
2025-10-20
EPSS Evaluated
2026-05-05
NVD
CVE-2025-40016
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux kernel *
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-UNKNOWN
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability in the Linux kernel's uvcvideo media driver involves improper handling of invalid or duplicate entity IDs in USB Video Class (UVC) devices. According to the UVC 1.1+ specification, each unit and terminal must have a unique non-zero ID. Previously, entities with invalid or zero IDs were ignored, which caused compatibility issues with some cameras and could lead to warnings or errors due to entities referring to themselves or invalid chains. The fix marks invalid entities with a special ID (UVC_INVALID_ENTITY_ID) to prevent these issues and improve stability.


How can this vulnerability impact me? :

This vulnerability can cause instability or errors in the Linux kernel when handling certain USB video devices that have invalid or duplicate entity IDs. It may lead to warnings, broken device functionality, or kernel warnings/errors when using incompatible cameras or devices that do not follow the UVC specification properly. Fixing this issue improves device compatibility and prevents kernel warnings or crashes related to these invalid entity IDs.


How can this vulnerability be detected on my network or system? Can you suggest some commands?

This vulnerability can be detected by monitoring kernel logs for warnings related to UVC entities with invalid or zero IDs. Specifically, look for messages such as 'Entity type for entity Output/Input X was not initialized!' or warnings from media_create_pad_link in the kernel log (dmesg). You can use the command 'dmesg | grep -i uvcvideo' or 'dmesg | grep -i media_create_pad_link' to find relevant warnings indicating the presence of invalid UVC entity IDs.


What immediate steps should I take to mitigate this vulnerability?

Immediate mitigation involves updating the Linux kernel to a version where this vulnerability is resolved, as the fix involves marking invalid UVC entities with UVC_INVALID_ENTITY_ID to prevent issues caused by zero or duplicated IDs. Until the update is applied, avoid using incompatible or non-compliant UVC devices that may trigger this issue.


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