# CVE-2026-90023: usb: gadget: f_mass_storage: fix null pointer dereference in fsg_common_set_num_buffers()

CVE-2026-90023 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-90023, released September 23, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-90023
- Priority: Routine
- CVSS: 5.5 (Moderate)
- EPSS: 0.0024
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 16, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-90023

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 13.5 (trixie) | 6.12.113-1 | [DEBIAN-CVE-2026-90023](https://patchblox.com/security/data/fix/linux/debian-cve-2026-90023.md) | Sep 23, 2026 |
| Linux | linux Debian 14 | 7.2.6-1 | [DEBIAN-CVE-2026-90023](https://patchblox.com/security/data/fix/linux/debian-cve-2026-90023.md) | Sep 23, 2026 |
| Linux | linux-6.12 Debian 12.15 (bookworm) | 6.12.113-1~deb12u1 | [DEBIAN-CVE-2026-90023](https://patchblox.com/security/data/fix/linux/debian-cve-2026-90023.md) | Sep 23, 2026 |

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Data as of 2026-11-08T19:12:23Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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